LONDON (AP) _ A good marriage can help a royal bridge the divide between a public and private life, Prince Philip said today at a banquet celebrating the 50th anniversary of his marriage to Queen Elizabeth II.

He did not mention the divorces of three of his children, although he said he was proud of all four.

Speaking at a luncheon at the Guildhall, the 76-year-old Duke of Edinburgh said people in royal life have ``to accept certain constraints and to accommodate to that gray area of existence between official and what is left of private life.''

``In such circumstances much can be done by an individual, but I am sufficiently old-fashioned to believe that a great deal more can be achieved by a partnership in marriage.

``It has been a challenge for us but, by trial and experience, I believe we have achieved a sensible division of labor and a good balance between our individual and joint interests,'' he said.

He also praised his children. In his talk, he did not mention the divorces of Charles, Andrew and Anne. Anne has remarried, and the third son, Edward, is a bachelor.

``I am, naturally, somewhat biased, but I think our children have all done rather well under very difficult and demanding circumstances and I hope I can be forgiven for feeling proud of them,'' Philip said.

``I am also encouraged to see what a good start the next generation is making.''

Guests at the luncheon included the 97-year-old Queen Mother, Princess Anne and her husband Capt. Timothy Laurence, and former prime ministers Lord Callaghan, Sir Edward Heath, John Major and Baroness Thatcher.