The Wellcome Library has copies of two letters to Francis Crick about his visit on 29 January – not the original invitation but one to agree the date (itself dated with the wrong year!) and another that crossed with one from Crick’s secretary about final arrangements:
The Wellcome references are:
Shelfmark: PP/CRI/E/1/11/3:Box 34
Reference number: b1818070x
Persistent URL: http://library.wellcome.ac.uk/player/b1818070x
Catalogue record: http://encore.wellcome.ac.uk/iii/encore/record/C__Rb1818070
[Hilary 1963] [Posters] [Opposing the SCM Mission] [Isis on the Humanists]
[Unmarried but pregnant] [Behaviour of the Press] [Women in the Union]