Philip was loftily dismissive. He said there would be scores of people there and I would be lucky to get more than five minutes with the Queen Mother after the meal. Chastened, I asked Sir Martin Gilliat, the Queen Mother's utterly charming Private Secretary, whether it would be all right for me to take notes. After all, I was Interviewing her for a book.

He thought for a moment. 'I think Her Majesty would think it rather odd,' he said.

Interpreting this, correctly I think, as a firm 'no', I put my notebook in my pocket and kept it there until what, for me, proved a memorable meetIng was ended. The minute I was back In the real world, I sat in St James's Park and wrote down everything I could remember. My memories of that day are based on those notes.

'Bidden' for 1pm, I arrived at two minutes to the hour, was ushered in by a uniformed footman and shown to a sort of staff common room.  where there were a lot of people having drinks. I chatted to Sir Alastair Aird, the Queen Mother's Comptroller, Sir Ralph Anstruther, her treasurer, and to Sir Martin Gilliat.

The South African ambassador arrived. My heart sank. Philip Ziegler was obviously right. It was going to be a bun-fight.

Then, suddenly, the news came that 'the Queen is down'. 

I found myself being escorted down a long corridor by Sir Alastair, an equerry and a lady-in-walting, and then being ushered into a drawing room and introduced to the Queen Mother, Princess Margaret and a corgi.  Just us.  The equerry brought me a dry sherry (it seemed the safe choice) and I found myself next to Princess Margaret and the corgi. The corgi looked at me ingratiatingly.

'I think she wants to be stroked,' saId the Princess, who was smoking a cigarette, left-handed, through a long black holder.

I said I'd heard about the royal corgis and wasn't sure It would be safe to stroke one.  Princess Margaret laughed and said this one was perfectly safe, so I patted it nervously on the head.

I knew that Princess Margaret was soon to be guest of honour at the annual dinner of the Crime Writers' Association, so I said something inane about it by way of trying to break more ice.

'Shall you be there?' she asked.

'Yes,' I said.

'Oh good,' she exclaimed smiling, 'So I shall have a friend,' 

Overhearing that we were both going to this event, the Queen Mother looked mildly envious. 'Lucky you,' she said, as lf she meant it.

They both turned out to be keen crime readers and avid fans of P. D. James. The Queen Mother, aged 90, was halfway through the author's latest book, which she proceeded to explain, plot-perfect. 

A servant came in. There was a delay with the first course. This presented no problem. The Queen Mother simply saId in that case we'd better all have another drink. I stuck with the dry sherry. Hers involved gin and was pink. I guessed Dubonnet had gone into it. Presently, the first course was ready, and we sat down at a round table, Sir Alastair, the equerry and the lady-in-waiting sat round one side. On the other, I sat between the Queen Mother and Princess Margaret.

Very occasionally in life, there are moments which you don't quite believe, when the only appropriate, and private, response is: 'Look, Mum, it's me.'  It should have been daunting beyond belief but it wasn't. They couldn't have been friendlier, funnier, more relaxed, or better at putting a nervous commoner and stranger at his ease.

We ate oeufs en cocotte on a bed of mushrooms, Portuguese chicken with a tomato and onion sauce, mashed potato and cabbage and a side salad with a blue cheese dressing. Pudding was a chocolate mousse with some sort of brandy butter, and we finished with coffee. Princess Margaret ate sparingly; her mother less so. The wine flowed. At the end of the meal cigarettes and cigars were offered, but only Princess Margaret smoked.

The main point of the exercise was to talk about Prince Philip. 'So difficult talking about family,' said the Queen Mother and, although we did discuss the Duke, the conversation ranged widely. We touched on animals - 'Dogs always forgive you,' she said - and the ghastliness of animal rights demonstrators.

'You used to wear a fur coat,' she said to Princess Margaret.

The Princess replied: 'If you did it now you'd have paint poured all over you.'

'Or be set on fire,' added her mother, and they both laughed.

We covered exaggerated stories about the Queen's wealth, and her mother joked: 'After all, it's not as if one can buy a hat with Hampton Court.'

Somehow, the visit In the Fifties of the Russian leaders Bulganin and Khrushchev came up. 'Oh, Bulge and Crush,' said the Queen Mother. 'No one In Britain could take them seriously.'

His mother-in-law and sister-in-law were funny, affectionate and frank when talking about Prince Philip. I told them ruefully how, a few days earlier, I had seen him at Holyroodhouse in Edinburgh, and he had asked how I was getting on with his biography. When I replied that it was fun, he had fixed me with that rather scary senior officer's stare and said: 'Fun?  It's not supposed to be fun.' 

The Queen Mother laughed and told me a story about Prince Philip 'ragging' at a Sunday morning preacher at Royal Lodge, Windsor, one day. Prince Philip knew the text better than the unfortunate cleric. The architect and artist Sir Hugh Casson, who had been present, later drew a cartoon of the incident.

'Isn't It interesting that Prince Philip is so keen on poetry,' I said to her. She looked at me quizzically, then leaned across to Princess Margaret and said: 'Did you know that he likes poetry?  I never knew that about him. It Just shows, everyone's got a secret.'

She told me that the Duke of Edinburgh was a very good public speaker, while she hated public speaking and got in a terrible state about it directly before she had to perform. She also said that Prince Philip was an accomplished painter. 'Only, of course, there's never enough time,' she added.

Talking of painting, the Queen Mother continued, she owned the best picture of Prince Philip anyone had ever done. It was a study by the Italian Pietro Annigoni for the portrait which hangs in Fishmonger's Hall. The finished work wasn't up to much, but the sketch was 'brilliant'.

'Philip and Annigoni didn't like each other,' she said. 'They presumably conversed in Annigoni's terrible fractured French. That's how he and Margaret communicated.'

Anyway, she said, would I like to see it?  It was upstairs. Princess Margaret, overhearing us, said she had never seen it and could she come, too. So when we had finished our meal, the Queen Mother shot to her feet and ushered Princess Margaret and I outside.

It was a very small lift and the three of us went up in it convulsed with giggles. On the top floor we got out and went to look at the Annigoni sketch of Prince Philip. It is excellent but fierce. You could guess that the artist and subject didn't get on.

Princess Margaret said It would make a marvellous cover picture for my book but the Queen Mother and I looked at each other and agreed that it wouldn't really do. Nevertheless, she gave me permission to reproduce it inside the book, where it looks good and very revealing of at least part of Prince Philip's character.

After we had discussed it for a while, the Queen Mother asked if I liked pictures and suggested we descended via the stairs, where she showed me her art collection on the walls of the staircase. We paused a while at a study by Graham Sutherland of the Queen Mother which he had started but never finished. (His notorious portrait of Winston Churchill was so ugly that Lady Churchill ordered its destruction.)

The sketch showed the Queen Mother chuckling. Suddenly, she said: 'It's very good, but he lost his nerve after the Winston Churchill fiasco. Someone's obviously told an awfully good joke.'

'No,' corrected Princess Margaret, 'You've obviously told an awfully good joke.'

I remember a Sickert and a Sisley.

'I always wanted a Sisley,' said the Queen Mother.

'I rather like it,' mused Princess Margaret.

'I think it's boring,' countered the Queen Mother.

Eventually, this magical tour was over and we were back at ground level. 'I'm afraid we haven't been able to help very much,' said the Queen Mother, smiling, 'but If there is anything...'

'If you do think of something, perhaps you could let me know,' I said.

'Oh, we'll send telegrams,' she replied, laughing.

So I thanked them and took my leave - as they say in royal circles.  It was a long walk down the hall to the front door. As I was about to leave the house, I turned back. She was still standing there, a tiny, regal figure, smiling that extraordinary, radiant, famous smile and waving. Just for me.

 DAILY MAIL, April 4, 2002