I already have a couple of the 5c/898s kicking about so that is easy though when I tried them they seemed a bit loose

Could this be what you need?

http://www.ebay.co.uk/itm/Vintage-RAF-Air-Ministry-Push-Button-Switch-Holder-5CW-4786-/170955906537?pt=UK_CPV_Aviation_SM&hash=item27cdc41de9