Regarding the Northover projector and other similar weapons, here are a couple of decent books;
http://www.amazon.co.uk/Last-Ditch-B.../dp/1853677302
http://www.amazon.co.uk/Real-Dads-Ar...toc/1848689144
I already own 'The Real Dad's Army' and I recently borrowed 'Last Ditch' from the library and its a fascinating read. I'll be investing in a copy when funds permit, but not just yet - road tax this month, exhaust fell off the car and February and the arrival of the next generation of T2K player is looming!