I always knew that launching myself onto the London gay scene would be a real mixed bag - scary, exciting, affirming, strange. I believed it would be a warm, camp and fuzzy place where I would be welcomed into the fold with eager arms. I expected to meet a plethora of interesting, diverse and accommodating people, united in the big happy family of queer. What I didn't expect was the ultra-trendiness of lesbian chic, the competitiveness of the school yard - and the fact that no one would believe me.

I moved to London after completing my degree in a little English town so dull that no one in their right mind would choose to go there. Suddenly I was free, and ready to explore the bisexual side I'd been aware of since realising I fancied Claire Danes and Jared Leto in 'My So Called Life'. After several false starts, a tricky bisexual love triangle and an unforgettable episode of queer speed dating, I finally found myself more or less on the scene - I knew where to go and had gay and bi friends. I'd also managed to persuade a spectacularly beautiful and intelligent woman to go out with me.

This was a major achievement. Having long hair, big boobs and ex- boyfriends apparently undermined my queer credentials and left me prone to being used as the curious woman's Big Gay Adventure. People of all persuasions had suggested my sexuality was a fad, or that I 'really liked men, right?' With bone fide girlfriend now in tow, I assumed that this would finally end.

I had been dating Kate for four days when we bumped in to Lorna, a woman my girlfriend had met on Gaydargirls (popular dating website for gay and bisexual women). Despite our obvious infatuation with one another, Lorna made increasingly inappropriate attempts to draw Kate in to one-on-one conversation. By the end of the night she'd formed a protective wall around my girlfriend and it was difficult to tell who was dating who. I later found out that she'd bluntly propositioned Kate, quite literally behind my back.

Despite my inclination to believe otherwise, Lorna's behaviour did not seem to be motivated by pure evil - rather, she'd acted on the belief that my bisexuality precluded a genuine attraction to women. Suggesting it was some kind of stumbling block, she'd asked, "Doesn't it bother you that Theresa's bisexual?" This - to my bisexual and equally feminine girlfriend whom she'd assumed was a devout lesbian, presumably on account of her short hair.

This set the tone for the next few weeks. Women would quite literally throw themselves at Kate whilst I stood gaping in horror. I was perceived as the straight mate, or a bit of dabbler - and my girlfriend fair game. I couldn't work out if it was bisexuality or my long hair that was the problem. Was it my label or my look? Neither seemed to permit me access to some exclusive club. There was either something fundamentally suspicious about me - or there was simply no honour among lesbians.

Biphobia towards bisexual women is usually far less violent and obvious than other forms of homophobia. It manifests itself as ridicule, pornographic fantasy or disbelief, resulting in a sense of exclusion and the erasure of identity. Bisexuality is perceived as an easy target for a bad joke. Jenny, 28, says, "I have found that people feel they can take the piss a bit, in a way they probably wouldn't with someone who was gay."

This suggests that bisexuality is simply not taken as seriously as other forms of non-heterosexual behaviour. The reluctance to see bisexuality as a valid and real orientation has also engendered the particularly irksome view that all bisexual women are indiscriminate, sex mad nymphomaniacs, or simply indulging in some lesbian fun until a penis arrives: "A lot people seem to think that if you're bisexual you have to sleep with women AND men, and so can't...stay with one person," says Jenny.

This assumption has inspired a deep sense of mistrust from some areas of the gay and lesbian community. Although Amy, 26, says she has never experienced biphobia on a personal level, she has encountered a number of profiles on Gaydar stating 'Don't contact me unless you are GAY'. She believes this comes from a fear of being used as someone's test run, and can understand 'why people would think bis are just seeing if they like it'.

'No bisexuals please' is a common and depressing theme in many lesbian personals. Jenny describes the following experience:

"Amongst lesbians - I used to think (biphobia) was a bit of a myth. Then I joined Gaydar. I looked up a girl I'd dated briefly and noticed that her profile specified 'no bisexuals'. I suppose there's a paranoid reading (i.e. that she added it after she met me), but I doubt it - there were never really any hard feelings."

It is worth adding at this point that Gaydargirls is actually an incredibly supportive and friendly online community. Neither I nor anyone I know has ever faced any outright hostility towards bisexual women and in my experience, many of the 'no bisexual' lesbians are prepared to make allowances. Rather, it's as if individuals are trying to protect themselves from being disappointed, hurt, or taken for a fool. This attitude isn't aggressive or deliberately offensive - just disappointing, hurtful and not a little disheartening.

For individuals new to the scene or their sexuality it can seem like one more hurdle to overcome. It's also incredibly unfair since, as Amy points out, "All people are not the same, so I try and think people will treat (others) as individuals, not take a blanket approach."

Maria, 50, says that there is general consent among her female bisexual friends that biphobia does exist. She has frequently encountered the view that bisexual women 'in the end always go away with guys, marry, have children and lead a sheltered life' and says; "Being bisexual (is perceived) as not to be committed to The Cause. There are many examples of circumstances where gay women that theoretically accept your claim of being bisexual, get horrified if you show up with your boyfriend."

The view that bisexual women will always ultimately choose a man is, Maria believes, because of the perception that it is easier to conform to society and choose a heterosexual lifestyle. This supports the idea that biphobia originates from insecurity. There is the tacit assumption that others are not always going to be brave enough to live what can be a difficult lifestyle - especially if choice is involved.

The issue is complicated further by the fact that bisexuality is frequently confused, or seen as inseparable, from polyamoury. It is also, as several lesbian friends have told me, often used as a useful stepping stone between heterosexuality and homosexuality. But as one of my friends remarked, "Everyone chooses in the end."

As Maria points out, there can be a strong feeling of betrayal to the cause. Certainly, homophobia against perceived gays and lesbians has assumed some extremely ugly, violent and deadly forms. Only recently a lesbian friend of ours was punched in the face by a male for 'looking gay'.

Since there has never been any real formation of a visible, easily identifiable bisexual look or lifestyle, bisexual women are more likely to avoid such aggression by 'fitting in' - whether they want to or not. In this way, bisexuality is perceived as a betrayal of the values, lifestyle and identity that has been fought for so hard by gay and lesbian activists.

Despite the view that bisexuals not only have their cake but eat it too, those leading bi lives can, in reality, experience a double sense of not belonging. Jane, 22, says, "For ages I didn't really know where to go - I felt unwelcome in lesbians clubs but didn't want to go to straight bars." Other women describe how difficult it can be to meet other bisexual women with whom to share their experiences.

However, things are changing. The last few years have seen the emergence or consolidation of a number of groups, websites, journals and festivals dedicated to bisexual lifestyles. In London and the UK these include Bi Community News (magazine), Bi Underground, the London Bisexual Women's Group (social groups) and Shybi (online community). Many venues and club nights now market themselves as queer, open-minded or inclusive. Finally, there seems to be a visible and viable bisexual community.

For women, one of the most supportive and long standing groups is the LBW group which has been running for over twenty years. This has provided a much needed haven for bisexual women of all ages and backgrounds, especially those new to the city. Jenny describes the impact of the group on her life:

"The bisexual group has been really important for me. I don't think it's really about wanting to hang out with bisexual women rather than lesbians, or gay men for that matter. It's more that it was welcoming, and somewhere I could go to meet people on my own when I moved down to London. In a way, it's a bit like coming out in university, when there's a whole committee devoted to helping you make friends and feel included. I haven't found that anywhere else in London. I wonder if bisexual women need that more than lesbians - is it easier to join the scene as a lesbian. I don't know."

For Maria, the group was also instrumental in developing a new social life in London:

"It did not occur to me that the best way to deal with the 'friends problem' was also the best way of dealing with my need to have girls in my life. I just feel silly for not having looked for the bisexual group earlier."

Such experiences certainly tally with my own. Whilst at one point it seemed that every lesbian in London wanted a piece of my girlfriend (no doubt a perception also due to my own insecurities), no-one at the group ever questioned my orientation, or my devotion to Kate. Apart from introducing me to some really amazing people, it also provided a useful way of easing myself in to a queer community which is, I still believe, diverse, creative, progressive, exciting and inclusive - but which can also be, perhaps understandably, self defensive.

Despite the undeniable benefits of a burgeoning bisexual community, I maintain reservations about the ever-increased splintering of the queer community. We live in an age of a dizzying proliferation of labels; of femmes and butches, bois and andros, tops and bottoms, dykes and power lesbians - and that's just the women. Whilst I welcome this diversity, I also believe that identity tags, including that of bisexual, need to be treated with caution and used as a means to include rather than exclude.

True, non-heterosexual people are not all the same and have just as diverse, myriad, and complex personalities, sexualities and lifestyles as anyone else - but we continue to share some important common goals and aims. The strength of the LGBT&F community and the reason for its success has been its ability to stick together, joyfully; to support its multifaceted membership and be more open-minded than other movements.

As queer identities grow, develop and prism in to countless opportunities, we need to ensure that they remain opportunities - that they do not become restrictive, and that we accept, use and exchange identity labels rather than letting them use us. To this end, petty phobias and inter-queer squabbling needs to be seriously addressed since it is this that undermines progress and development, not the occasional flighty or confused bisexual.

If bisexuality has taught me anything, it is the importance of choice when it comes to sexual practice and lifestyle. 'Bisexual' is not an exhaustive identity label and comes with its own limitations. To this end I often find myself adopting different labels to suit different stages of my life which is, I believe, something a bisexual identity can accommodate. We just need to ensure that as our community grows, the boundaries do no shrink or restrict our crucial ability to exercise free will.

As Maria says: "If you have a choice, be bisexual."