Oxford librarian Prof John Simmons did not forget his old college in his will. But he has set All Souls a monumental challenge before it can hope to receive a share of his £888,000 estate Prof Simmons had always maintained that the college had made a terrible mistake when it moved its famous sundial designed by Christopher Wren from a wall of the chapel.

Under the terms of his will, All Souls must move the sundial, to its original place if it is to receive any of his money.

Prof Simmons, who died last year, aged 90, was a leading Slavonic scholar, who spent much of his career in Oxford libraries in charge of Slavonic books.

He was also an expert on sundials and shared a 130-year grievance with other Oxford traditionalists about the college's treatment of the huge sundial, which was designed by the architect of St Paul's Cathedral in 1658.

Recognised as one of the most beautiful in the world, it was moved from the southern chapel wall, in the front quadrangle, to the Codrington Library in the 1870s.

The relocation had two consequences. The first was that Wren's dial, once so accurate that the Oxford watch and clockmakers used it to check their timepieces, no longer told the true time.

The other was that members of the college have complained ever since that the sundial upset the symmetry of the North Quad.

Prof Simmons's will says that part of his estate, a sum not yet specified, will go to the college on condition that the sundial is "re-erected where it was originally positioned by Sir Christopher Wren, that is to say over the south front of the college Chapel".

Prof Simmons, who lived in Upland Park Road, North Oxford, served at various times as a librarian archivist, lecturer and senior research fellow at All Souls.

He left a share of his estate to the Bodleian Library, on condition that three funds "for specific purposes" are created. St Antony's and The Queen's colleges and the Taylorian Institution are all left £10,000 each.

One of his proudest achievements had been building up collections of Russian books in the Bodleian and Taylorian libraries. A world authority on the study of paper, in later years he published work on the history of All Souls and its buildings. His wife died in 1999.

The bursar of All Souls, Tom Seaman, said the college had not yet seen the will.

He said: "We have a pamphlet which Prof Simmons prepared several years ago, making his argument for moving the sundial from its current position in the Great Quad to its former position in the front Quad."