A survey was promptly done and a quote promptly produced.
The work (stripping plaster, injecting damp course, adding a plastic membrane, replastering) was also done promptly, tidily, to a good standard and to budget. The work came with a 30 year guarantee from Westminster Guarantee Protection (Trustees) Ltd. (as far as I can tell, this is good insurance, but it obviously has not been tested yet).
I can recommend Tommy as hardworking, trustworthy and straightforward to deal with, and I intend to use him again in the near future.