Had a chance to talk to John Fawcett who told me he was happily retired and not doing any gun work. His son who now runs the business has quite enough work with repairs for his customers and is not taking on any outside work in the foreseeable future.
The sleeving specialists are becoming very thin on the ground in the UK.
My go-to sleever retired through ill-health some years back and the remaining business is struggling to keep abreast of the trade work they have.
Another person I know of is still taking on sleeving work but by necessity it takes a low priority and one has to be very patient.
The only others are the true, time served barrel-makers like Blacker. Obviously the work is of the highest order but about twice the price of the more normal gun works. They also take their time and patience is a real necessity!!