Hi Rob,
I was doing a lot of overhauls on Militants in the late 70's, in the REME Wksps and I remember the cloth filters, but there was a modification which I recollect doing, to replace the filter assembly with a more modern CAV type with a better filter element. Could have been due to depleted stocks of cloth filters in Ordnance stores no doubt.
Tanker looking great!
regards, Richard