I have recently come across an autobiography written by a Mr. JOHN N. BARCOCK, part of which covers a period between 1956 to 1966 when he worked at Harrison and sons of High Wycombe.
http://jnbarcock.co.uk/My%20Times%20at% ... 0Ltd..html
The report is of a personal nature but it also gives some fascinating details relating to the firms history etc.
I thought you might be interested in reading it If you are not already aware of his writings, there may be some additional information within the text that you are unaware of.

Imagine the stamps that these people must have produced over the years, there was no computers in those days !

Thank you John for your recollections !
WM.