23 thru 26 are Bell XV-3 of 1955 (4147 A/C 1 & 4148 A/C 2). 38 & 39 are the same Bristol Type 164 Brigand B Mk.1 of which "167 were built of all types when production ceased in 1949".
Sources: "VSTOL" Mike Rogers and "The Encyclopedia of World Aircraft", Edited by David Donald.