Established in 1961
As well as county maps you can also collect early road maps. All the county maps of the British Isles up until the reign of Charles II did not show any roads. But in 1675 John Ogilby published his Britannia which was an atlas in which the roads of England and Wales were mapped for the first time. None of Scotland. This must have been a most time consuming and exhausting survey. But it meant that after this period county map started to include roads. Britannia was a heavy folio sized volume. Very difficult to carry around with you. But after 1700 there started to be published a number of smaller atlases with road maps based on Ogilby's survey. Much more convenient for the traveller.
If your Interest is British County maps then you will probably find my ongoing project to offer more information on the amazing cartographers whose works you might want to collect. Still in its infancy and a lot of work to do but please check it out.