"Of course not! It has an expiry date on it - that's when it will become invalid"
That, of course, is not necessarily true; licences may be withdrawn at any time. The last issue of the old-form paper driving licences was in 1998, thus such a licence having been issued to a 17-year old at that time could have an expiration date in 2051. At some time before that date all paper licences may be subject to compulsory surrender, as per the amending provisions of S.39 Road Safety Act 2006 in respect of S.98A Road Traffic Act 1988.
http://www.legislatio...a/1988/52/section/98A
Compulsory surrender of old-form driving licences has not yet been enacted and is not imminent. I recall reading a Parliament consultation paper predicting withdrawal of the paper licence within the next 20 years.