Dear Meg,
You are most likely to obtain the necessary information from Citroën Heritage (the Conservatoire) in Aulnay.
If you send them appropriate vehicle details (and a fee, of course) they will supply a “Certificate of Identification” which is acceptable to registration authorities.
Relevant information can be found on the website of Amicale Citroën International (ACI). http://amicale-citroen-internationale.org/
The downloadable pdf document contains an application form and explains the process and details of the information you are required to supply. The following link will take you directly to the pdf :
http://amicale-citroen-internationale.org/wp-content/uploads/2013/03/Catalogue-products-UK.pdf
Hope this helps, Noah.
Anonymous