Can anyone advise reference information for booklet packaging for wrappers, packet and parcel labels? (WB, PL, RL references etc..) trying to find a consolidated listing particularly for window booklets and 50p & £1 vending booklets

You need the Bookmark Catalogue which was published by the Great Britain Decimal Stamp Book Study Circle, 7th edition 1999 with 2000 supplement. Totally comprehensive of everything issued with explanations of production,perforation, errors etc - all in extraordinary detail and has full packaging descriptions for all from 1971 to 1999. That circle is now part of the Modern British Philatelic Circle and the catalogue editor is Hanns Fasching - I will ask him how/where you might get a catalogue. My email is iph@harvey27.co.uk so better to make direct contact rather than messing about with this!!
Regards, Ian

Many thanks