We always went to the same branch of John Lewis for MasterQ's shoes, where the staff were also trained to measure and fit very carefully. One of the advantages of going to JL was that they seemed to stock a very wide range of makes, one year he wore Start-rite, the next Clarks, the next Hush Puppies, and so on - the staff were very helpful and knowledgeable, I found.

(I still have his first pair, he is 18 this year. SillySuzy!)