David Giles, 43, used to dread sleeping away from home. “In the mornings I’d wake up and be surrounded by handfuls of skin. I was so embarrassed. If I was at a hotel or someone’s house I’d have to frantically sweep the bed.”

Giles, a salesman for a multinational oil company, has severe psoriasis, a skin disorder that can leave its sufferers covered in scaly, red scabs and constantly shedding skin that looks like dried wax as it dies and falls off.

He developed it in his early twenties and by his early forties, with his self-esteem deflated and his skin peeling, he had reached the end of his tether. Psoriasis-associated arthritis left him in too much pain to do the globe-trotting job he loved and his personal life was not much better: “I was going through a rough patch in my marriage and I thought, if I do end up alone, who will ever want me like this, covered in scabs? They would never want to see me without my clothes on.”

But then came the “biologics”, the drugs that Giles says have transformed his life. “It sounds clichéd and sensationalist but these drugs are a miracle; I am now exactly as a fat 43-year-old should be.”

Earlier this month, after two years of deliberation, the National Institute for Health and Clinical Excellence (NICE), the group that decides whether a drug works and if it’s worth spending NHS money on, decided that providing two of these biologic drugs — Raptiva (efalizumab) and Enbrel (etanercept) — is cost-effective for patients with severe psoriasis. They are now available on the NHS.

Psoriasis is caused by the immune system attacking skin cells and, while previous drugs have been chemical-based, the new biologic drugs are based on proteins found in the human body.

Giles is convinced that his psoriasis was triggered by stress after a bad fire. “I was working in a pub in Kent when I was 23 and there was a very serious fire. No one was killed but two girls were very badly injured when they jumped from the top of the building; one broke her ankles and the other her back, and the building was levelled.”

The fire left him shaken and traumatised, and not long after this he started to see white marks under his nails, then scaly patches on his elbows and knees, which were annoying but easily covered up with long-sleeve tops and long trousers. Life went on as normal. He married and started a family but, as he approached the age of 30, his feet started to hurt.

“The balls of my feet became very painful and when my hobbling became worse, my employer sent me to a specialist. When he diagnosed psoriasis-associated arthritis I was relieved; I thought that I might have multiple sclerosis.”

But this relief was short-lived as over the next ten years his psoriasis and arthritis got pro- gressively worse until scabs that resembled burns covered 70 per cent of his body.

He needed to plan meticulously his frequent job trips, ensuring that he had a rest period after each flight to allow the pain of his stiff and swollen joints — for which he was taking strong pain medication — to subside.

Although he was fortunate that the skin on his face wasn’t badly affected, the rest of his body was covered. Before business meetings he’d fret about shaking hands and the colour of the boardroom carpet.

“I’d slap on steroid and vitamin D creams two or three days before an important meeting, and when I was there I would shake hands quickly and then keep them out of sight. If there was a dark carpet, it was awful, as my skin would flake off and fall down my trouser leg on to the floor.”