The time is 5.30pm. You have summoned up the courage to join your colleagues for post-work drinks – or perhaps, more accurately, failed to summon up the courage to say no. Picking up your pint glass and absent-mindedly wiping the rim clean of germs, you transfer the drink from your right hand to your left, so the sensation of glass on skin feels symmetrical. For the next sip, you pick up the glass with your left hand and transfer it to your right. Someone asks what you're doing. You stare quietly into your drink and say nothing.
OCD affects as many as two to three per cent of the UK population (around 1.2 to 1.8 million) but estimates vary because of the understandable reluctance of sufferers to seek help. It can take people with OCD years, even decades, to admit to anyone that they have the condition. Another sufferer, Colin Putney, 47, confessed to me: "I covered it up for 35 years. I never admitted it to my family, friends or girlfriends. It's a secret illness. People are embarrassed by their thoughts."
This silence is unsurprising. OCD is easily - too easily - dismissed by those who don't understand how devastating it can be. Without the information to hand, and sadly the truth of OCD is not exposed nearly as much as it should be, the condition sounds to many like little more than an irritation – even a quirk of personality. What's the problem? You're only washing your hands a bit more often and checking you haven't left the oven on.
Worryingly, the lack of public information can mean serious consequences for sufferers. John was refused a Disability Living Allowance no fewer than five times. "The medical world and the Government don't realise the severity of it," he told me. "They said, 'Oh yeah, I know someone with that. I've got it a bit; we've all got it a bit, haven't we?'"
A common perception is that OCD symptoms are just idiosyncrasies; personal superstition. As Victoria Beckham once explained, her husband David – who in her own articulate words has "that obsessive-compulsive thing" – demands a co-ordinated fridge: "If there are three cans of Diet Coke, he'd throw one away rather than having three – because it has to be an even number."
It is possible to have these feelings without having OCD, but that doesn't mean OCD doesn't exist. And it would be a lot better publicised if the likes of Beckham and fellow 'celebrity sufferers' Paul Gascoigne, Jessica Alba and Cameron Diaz – who used to open doors with her elbows to avoid touching supposedly germ-infested doorknobs with her hands – would openly talk about their problems.
But why should we expect them to? It's hard enough for anyone to admit to having OCD, let alone with a hundred cameras shoved in your face. Fortunately, and thanks to a lot of help from my girlfriend, coming out with OCD didn't take me long: just a couple of years after first realising I had it, at university. Still, that's a couple of years in which I must have come across to people as even weirder than usual.
Was it easy to say I had OCD, even to my closest friends? No – even though a number remarked that they'd realised something was odd, casually replying, "Oh, you mean when you act weird all the time?" I suppose I should be touched they noticed, although it felt uncomfortable at the time – like someone had been prying inside my mind.
Still, at least coming out of my obsessively clean closet stopped some people thinking my actions were symptoms of nothing but rudeness – though others weren't as easily convinced. To a few of my confidants, OCD wasn't a debilitating condition, and my insistence on wiping the rim of my glass clean after they had drunk from it was still a personal insult in which I accused them of poor hygiene. One person licked the rim of said glass in protest. For some reason we're not in contact any more.
But although it was a still a lonely time for me, trapped in my head with thoughts that didn't feel like my own, I received a lot of support from friends and my family, who were equally unsurprised at the 'news'. I felt better for talking about it, though I could understand why many choose not to. It's one of the hardest things I've ever had to do.
It made me wonder, though: given the magic ability to cure myself at the touch of a button, a hypothetical scenario mooted by Stephen Fry in his pieces on depression, would I eradicate my OCD? Would I press the button? I've always said no: that would change who I am. But to suddenly stop counting bricks in a wall and staring at doors for minutes at a time trying to take in that they're safely locked? I can't say I wouldn't be tempted.