The modern manuscripts (dated 1526-late 20th century) in the Syon Abbey Medieval and Modern Manuscript Collection (reference number EUL MS 262), which are looked after by Special Collections at the University of Exeter, have now been catalogued at item level and are available to search via an online catalogue. It is hoped that the new catalogue entries will make the manuscripts much more discoverable and accessible to future users. For more information, a blog post about the newly catalogued manuscripts (including images!) can be read here.
The Syon Abbey archive can be searched in the online catalogue using the reference number: EUL MS 389.