Jmoore
Might be a bit of work to get that info.
So far I have confirmation that they may exist, together with an indication that he might sell.
One has previously been cannibalised to suppy a graticle assembly for one of my scopes.
As far as serial numbers go, I know that I have the following in my small group.
No 32 Mk1 #2707 W.Watson & Son
No 32 Mk1 #6066 Kershaw Ltd
No 32 Mk2 #10930 H.B.M. Co
No 32 Mk2 #10859 H.B.M. Co
No 32 Mk2/1 #347 Vickers U.I.C.
No 42 Mk1 #1286 H.B.M. Co
No 53 Mk1 #583 A.K & S
No 55 Mk1 #58 R.S.A.
A long way from the 21 or so needed to have a full set
Cheers
Paul