Soon after completing it, Holbein took it to Switzerland and gave it to More's friend Erasmus, so he could see how the family was getting on. Erasmus adored it and said it made him feel as if he was back in the Chelsea household. It has remained in Basel , Switzerland , ever since and has been lent by the city's Kunstmuseum. "It is amazingly exciting to have it here in London ," said the show's curator, Susan Foister. "The painting's destruction was very sad but at least we have this wonderful drawing which gives us a good idea of the composition and the background in what was the family home in Chelsea ."

More, a staunch Catholic, was Henry VIII's adviser, secretary and then finally the first layman to be chancellor after Cardinal Wolsey refused to help annul Henry's marriage to Catherine of Aragon (divorced).

In 1515 More published what has been called one of the first classics of English historiography, The History of Richard III, and the following year he published his most famous work, Utopia - a description of an island ruled by reason, free of poverty and war. But he fell out of favour with Henry and was beheaded in 1535 for opposing Henry's marriage to Anne Boleyn (beheaded). Erasmus, who had a profound influence on the Reformation, was a good friend of More and dedicated his most famous work to to him - The Praise of Folly, a satire on the Catholic church.

For Erasmus the drawing was the 16th century equivalent of looking at a family photograph. There were also annotations in old German by Holbein pointing out proposed changes as well as a brown ink drawing of a monkey in the bottom right hand corner. More had a small zoo and was especially fond of one particular monkey. The drawing - Designs For More Family Group - will be shown alongside a series of preparatory chalk drawings of individual More family members which are held in the royal collection at Windsor.

"This is the biggest exhibition for over 50 years and there are paintings in the exhibition that have not been seen here for many years," said Dr Foister."We see Holbeins everywhere we go and we're pretty thrilled with what we've managed to borrow."

Holbein is regarded as the first truly great painter to work in England . His hesitant arrival in 1526 in effect brought the Renaissance from continental Europe to Britain .

When, aged about 29, he arrived to meet his future patron Sir Thomas More there were fears he would not get much work. More wrote to his friend: "Your painter, dearest Erasmus, is a wonderful artist, but I fear that he is not likely to find England so abundantly fertile as he had hoped; although I will do what I can to prevent him finding it quite barren."