Dear John Pearson,
I'll certainly have a look regarding your Alvis number questions, but as far as I'm aware these are not on any of the Saracen plates.
Just to advise and clarify that these were 'not' recovered from the ranges, but originated from from a private engineer's workshop who purchased approxmately 500 Saracens, over 250 Ferrets, all the Shorlands & the last 89 Saladins from MoD.
Regards,
Brandone