Brum,
The only document I carry on a regular basis is my plastic driving licence and that is only because it conveniently fits into my wallet.
It has always been an offence not to be able to produce your
documents on request, however it is not a legal requirement to carry them, therfore the Police will allow 7 clear days ie. commencing at midnight on the day of the request, for the documents to be presented at a suitable Police Station.
The Police do have access to driver licence, insurance and MOT databases and will normally use these to check a persons status at the roadside, rather than inconvenience them, however as with all systems, they are only as good as the information input, not all insurance companies subscribe and are not guaranteed to be 100% accurate.
Thus, there will still be instances where "producers" will be used and the 7 day rule applies.
If however, a genuine motorist on holiday has forgotten to take their licence away and can't produce in that time period, the cop can mark the paperwork up to that effect and give a longer period of time before raising a summons to court.
If you are away from home for longer periods, the onus remains with the driver to be able to produce the documents, so it would make sense to carry the original documents with you or at least have a system of being able to get the documents sent to you, as the licence especially has to be produced in person.
Visitors from abroad will be required to produce original documentation at the roadside or risk being arrested and taken to a Police station, where enquiries will be made back with the home country, and this could require a lengthy stay if the relevant Foreign departments are closed for the night,
Ken.