XM346 was one of several JP3s from the first production batch, SOC middle/late 1969 and sent for rescue/fire practice at Leeming, Linton-on-Ouse, Catterick and Little Rissington.
None of these a/c were allocated an "M" number.
The BAC 167 Strikemaster first flew at Warton on 26th October 1967.
There is nothing in XM346's service history suggesting use by BAC Warton.
Following the usual procedure, AAEE, Hunting Aircraft, XM346 served with CFS, 6.FTS and finally RAFC. There is a photo on a web-site(Google "XM346 Jet Provost") showing XM346 with 6.FTS coded "26" at Odiham in September 1962.
The comments relating to the fire dump at Cranwell earlier in this thread may be relevent here.
A public road led to the main gate at Thorney Island to allow access to Little Thorney church. The JP3 was easily seen close to this road on the left hand side just as one came over a small bridge. Did the station CO's wife or others not like the sight of this inoffensive a/c, so it was painted with whatever paint was to hand in order to "camouflage" it?
Ciarain.