By Jane Dreaper BBC News, health correspondent

Melly has peformed for many decades

He is 80, and has been determined to continue appearing on stage - despite having lung cancer and vascular dementia, which affects the brain after small strokes.

On 10 June, George Melly will lead a special concert at the 100 Club in London, to raise money for the charity For Dementia - and there are rumours of some big name surprise guests.

Dementia is nothing to be ashamed of. And right now, George is still alive and still enjoying life Diana Melly Mellys' interview

I spent some time with George and his wife Diana, as they got ready for a recent concert at the Landmark Arts Centre in Teddington.

Diana Melly is making scrambled egg with just one egg, in the tiniest of pans.

She knows that if she puts too much food on her husband's plate, he won't eat it.

"George's attitude to food has become extremely child-like," she tells me.

"Two months ago, he had a fishcake - now he has a fishfinger. He always wants his toast cut into little triangles."

Not easy

Being creative with these small-scale meals keeps Diana Melly busy - and enables her to express her care and love for her husband of more than 40 years.

She admits she doesn't find it easy to be on her own at the moment.

Sometimes it's as if a spotlight came on and lit up a bit - other times it's off George Melly

A documentary crew are filming with the Mellys at the moment - and there are also appointments with social workers and district nurses.

Diana said: "Eventually - possibly quite soon - we'll have a hospital bed downstairs, so George can be near the kitchen.

"Dementia is nothing to be ashamed of. And right now, George is still alive and still enjoying life."

I climb a couple of flights of stairs to see George Melly, who is lying in bed.

I nearly trip over his ashtray. He tells me he has no plans to give up his heavy smoking habit: "Without a cigarette, I wouldn't find life so agreeable".

He assures me that, despite his failing voice, he is keen to chat.

'I dream a lot'

"My dementia isn't constant," he said. "Sometimes it's as if a spotlight came on and lit up a bit - other times it's off.

"I dream a lot, which is important to surrealists," he adds, referring to the art movement he's strongly supported and written about over the years.

Melly has always been flamboyant

"I wake never quite sure if the dreams are real or dreams - and it takes me a long time lying here, to sort it out.

"I mostly remember the songs, because I've sung them for so long.

"My band leader, Digby Fairweather, is a terrible optimist, especially when he's had a drink - and he always says each performance is the best I've ever done."

Diana Melly is by the bedside during this interview - she's smiling and relieved that her husband is lucid.

Just a few hours later, George Melly is on stage, resplendent in a bright red kaftan.

He steps out of his wheelchair at one point - joking with the audience that he did it just to alarm them.

The people closest to George Melly know the time will soon come when his physical frailty will mean he'll have to abandon his live appearances.

But he has given his utmost to tonight's performance - and the audience rise from their seats to show their appreciation.