It has been a big few weeks for 90th birthdays. First the Duke of Edinburgh hit the magic number, but amid all the celebrations he still found time to send a letter of congratulations to mark the birthday of fellow nonagenarian, Sir Sigmund Sternberg.

Like Prince Philip, Sternberg is attempting to rein in his many activities now he has entered his 10th decade. But there is a lot to rein in. Sternberg, known affectionately as Siggy by all those who know him, has for many years been almost a one-man industry. He is possibly best known for his chairmanship of the International Council of Christians of Jews and his foundation of the Three Faiths Forum, which provides a platform for Christians, Muslims and Jews. He also launched the Sternberg Centre for Judaism, had a long career at the Board of Deputies, has been actively involved in the Labour Party, backed the Hebrew University and has been decorated by just about everyone who matters, including the Queen and the Pope.

In the sitting room of Sternberg's rather grand north London residence, we sit surrounded by photos of him meeting the great and good. His wife, Lady Hazel, fetches a few of the many medals he has collected over the years - there are enough, it seems, to fill the Old Trafford trophy room.

Sternberg was born and raised in Hungary and arrived in Britain on the eve of the Second World War as an 18-year-old. He may have been in this country since 1939, but his accent is still pure Budapest.

The son of an antiques dealer, he had a comfortable upbringing. He is reticent about the details but states that: "I did not see my future in Hungary, I saw it here in the UK". He adds that while he and his family were Zionists, he did not see his future in Israel either.

Life was initially not easy in London where he was faced with the rather pressing problem of how to make a living. "I was known as a friendly enemy alien. It sounds funny doesn't it," he says. Funny maybe, but serious too. He was not allowed to seek paid employment, so instead he began to trade in scrap metal. He was soon thriving. He had "business in the blood," he says, adding: "I always knew I was going to go into business."

Sternberg immersed himself in the war effort. He was barred from the armed forces so he joined the Civil Defence Force instead. He was doing what was deemed essential war work, and by the time peace came he was already showing himself adept at turning a profit. One story he enjoys telling involves a consignment of hospital equipment that he bought at auction on a hunch and managed to sell at a subsequent sale without ever working out what its use was. In 1949 he was rewarded with a British passport.

His company, Ingot Metal Investments, was making good money, so much so that by 1965, a still relatively youthful Sternberg felt he had more than enough to get by on, and sold up most of his interests to devote his time to charitable interests, the first being his own Sternberg Foundation.

In the 1970s, he was presented with a challenge - to turn the moribund Council of Christians and Jews into a flourishing organisation. With his talent for organisation and networking, it was practically a given. He says: "I always wanted that there should be good relations between Christians and Jews. Hatred never leads anywhere. Now we have the Muslims involved through the Three Faiths Forum. And it has been a great success."

It is his aptitude for "getting along with people" as well as his tenacity which he reckons has enabled him to get results over the years. It has also gained him huge numbers of honours from those he has helped. One of his most treasured is the Papal knighthood was awarded in 1985 for services to Jewish-Catholic relations. He is, as far as he knows, the only Jew to hold one.

Although justifiably proud of this award and others, he is more interested in what the honours have enabled him to achieve. "They open doors. It's not that I care for medals, but if you put them to good use then good can come out of it."

There are two situations to which he might well be referring. He used his influence to persuade the Vatican, under Pope John-Paul II, to recognise Israel in 1994. He recalls: "I met all the Catholic leaders at the Vatican. I spoke on Vatican Radio and in the end they just got so tired of me that they said: 'OK, let's talk about recognition'."

His other notable achievement was over a Carmelite Convent set up in the grounds of Auschwitz in 1984 causing outrage in the Jewish world. Again he used his contacts with the Catholic Church to defuse the row. "I negotiated with Cardinal Jozef Glemp. At first it was difficult but eventually he came to see us at the Sternberg Centre. He said: 'This is a nice Jewish home'."

He is an admirer of Chief Rabbi Lord Sacks despite being long-time president of the Reform Synagogue of Great Britain. He says: "I was brought up as an Orthodox Jew but I couldn't deal with leaving my car around the corner from shul. I didn't want to pretend. I thought if I join the Reform movement I can make my own rules."

Sternberg does not get to synagogue so much these days. His frailty means that his outings are more limited. He is content with his contribution and happy that the baton has been passed to a new generation. He acknowledges that "at some point, you have to call a halt".

However, Lady Hazel does not completely concur. "He never stops," she laughs. "Even now."