Normally when one is looking for information on a given subject including philately, a specialised book is usually sought.
Most of the information it contains has been gathered over the years and has been compiled in some kind of readable order, this source of information usually comes from records, old magazines, journals and individual reports.
Here is some information with regards to Harrison and sons the renowned security printers of High Wycombe who for many years produced stamps for many different countries throughout the world.
The source comes from part of an autobiography made by John Neville Barcock who worked at the printing works for 10-years between 1956 to 1966, he has been very meticulous taking care to include as much as possible that he can remember relating to his time there.
I sent him an email some time ago, but I have never had any response.
I am sure he would have liked you to read of his escapades which also gives invaluable information of times gone by.http://jnbarcock.co.uk/My%20Times%2...%20Ltd..html
Here is a picture of the staff at an earlier date (1933), remember that in those days there was no computers!
Imagine the stamps that these people must have produced over the years.
The philatelic part of the autobiography has been stored on the UK web archive and national archives network in order for the need of future reference.
Thank you John for your dedication and a great piece of historical literature appertaining to a brilliant company of the past.