Just a couple of observations from my log book, which show that from 1984 (when I joined) to 1986, at 617 VGS, Manston, I flew Mk3s WT910, WT917 and bizarrely, XE801, which your list shows as written off in 1978!
WT910 and WT917 must therefore have 617 added to their lists of VGSs.
XN246 and T21 XN155 were also on the fleet.