Three administrative letters from the MRC concerning foreign currency arrangements for an unspecified visit to Madrid in 1956.
The letters show that on leaving Madrid, Crick travelled to France before returning to England. "The Bank will, I'm afraid, require the date of your arrival and departure from each country you plan to visit. These will not necessarily be the dates of your official visit, as you are proposing to take a holiday at the same time...."
See Brenda Maddox, Rosalind Franklin: The Dark Lady of DNA (2002), which notes Franklin’s attendance (Madrid, April 1956) at an International Union of Crystallography Symposium (‘Structures on a Scale between the Atomic and Microscopic Dimensions’). Crick is also noted as attending. Maddox, p. 268: “When the meeting was over, Rosalind decided to go with Francis and Odile Crick on a tour of southern Spain.” Maddox’s biography also contains a group photograph, taken at the Symposium (2 April, 1956), of Crick, Don Caspar, Aaron Klug, Rosalind Franklin, Odile Crick and John Kendrew.