THE FIRST place the social security inspector looked was the kitchen cupboard. He rummaged among the cereal packets, jars of jam and baked bean tins. Unfortunately Tim and Lisa hadn't thought to mark them 'his' and 'hers'. This was enough to convince him that they shared food and so were more than just good friends.

A lot hinged on the judgement of the 'adjudication officer' (the Department of Social Security prefers 'adjudicator' to 'inspector', perhaps because it doesn't sound like a rank in the SS). If Tim and Lisa were found to be living life together 'like a marriage' - or what the DSS euphemistically terms, as 'partners' - Tim would be ineligible for income support because Lisa would be expected to provide for him. But Tim and Lisa were flatmates, not lovers or 'partners', and although she was obviously sympathetic when he lost his job as a designer, that didn't run to covering his part of the mortgage.

Tim applied for income support when he was made redundant. One week later the adjudicator called round for a cup of tea and to investigate the pair's domestic arrangements. It became the most frustrating and seemingly pointless half- hour that Tim and Lisa had ever spent.

'All our friends and family obviously know we're just good mates,' says an exasperated Lisa. 'But proving it is different and very, very difficult.'

If Tim's need for benefits hadn't been so crucial, the visit would have been hilarious. Lisa believes the most damning piece of evidence was the discovery that they shared baked beans from the same can. 'The guy was rooting around the cupboard and inside the fridge and asking us who had bought what,' says Lisa. 'When I told him we sometimes shopped and cooked for each other his face lit up.' Enjoying meals together seems to be the prerogative of 'partners' only.

According to the general manager of one benefits agency, home visits by one of approximately 800 adjudicators are 'standard legislation to help safeguard the government's purse'. Social security fraud teams prevented half a billion pounds of taxpayers' money reaching benefits cheats last year. But how accurate can these checks be?

Tim and Lisa met at college 13 years ago and for the last five years have shared the mortgage on a two- bedroomed flat in Brixton, each stumping up pounds 250 towards the monthly payments. Tim has been going out with his present girlfriend, Sophie, who lives in north London, for two years. Lisa has been dating Nick, who lives in nearby Peckham, for five years.

But the adjudicator probing Tim and Lisa's relationship obviously seemed to believe differently. 'When we told him how long we had known each other he seemed to assume we must be sleeping together,' says Lisa, although he didn't actually ask if they were having a sexual relationship - that is not allowed under DSS guidelines.

If the baked-bean tin incident was farce, it was nothing to what followed. The adjudicator was encouraged by the discovery of shared cereals and jam. 'So you eat together, do you?' 'Yes, sometimes,' said Tim hesitantly. 'At the same table?' 'We've only got one.' 'And wash up?' 'We take it in turns.' 'What about going out? Do you go out together?' 'Yes, of course, we're friends.'

Tim and Lisa could see that the line of questioning was going against them, but they still had their trump card: the separate bedrooms. In the meantime, they would have to face a further barrage of questions. 'Who pays the bills?' asked the adjudicator. 'We split the gas, electricity and phone,' said Lisa. 'You don't have a kitty then?' 'No, we just halve them.' 'Ah, but who actually pays it?' 'What do you mean?' 'Who goes to the post office?' 'No one, we post them.' 'Oh, I see.' (long pause) 'Have you ever discussed marriage?'

Losing patience, Lisa snatched the cup of tea from the adjudicator's hand and pushed him down the hallway to show him their separate beds in separate bedrooms. 'There's absolutely no point in me going in there,' he said, standing his ground. 'It's easy to move beds.' He wouldn't even peep inside, and therefore missed the opportunity to see a photo of Sophie propped up on Tim's bedside table.

But if the adjudicator didn't want to go into the bedrooms, Tim and Lisa could at least find evidence for him. They searched frantically for intimate photos of themselves with their respective beaus. But when they got back to the kitchen their hearts sank. The adjudicator was scanning the cork noticeboard. Unfortunately, pinned among the unpaid bills, invites and notes to the milkman was a Polaroid of Tim giving Lisa a friendly peck on the cheek. Why hadn't they taken it down?

The adjudicator's mind was made up. 'Those could be old flames,' he said, giving the photos Tim and Lisa were clutching a cursory glance. 'This, on the other hand,' he said, triumphantly pointing to the Polaroid, 'proves something.'

Tim and Lisa argued, but the innocent photo, ironically snapped by Lisa's boyfriend, Nick, during a picnic, had suddenly become a damaging piece of evidence. 'We said if we had something to hide, we wouldn't have left the photo in plain view,' says Lisa. 'But that logic didn't seem to satisfy him. I felt so utterly helpless and angry after such an invasion of privacy.'

Tim's claim was turned down because he was judged to be living with a 'partner'. He was told he had the right of appeal, but didn't bother because he was busy applying for jobs. Fortunately, he landed another one and three months later moved out to live with his real 'partner', Sophie. Lisa hasn't yet advertised for a flatmate to share the mortgage.