[Sierra Mike] I answer to INJ mostly. In fact elsewhere I tend to be just NotJohn - Im not sure why I've got the 'Im' in the Morniverse. I'm also a bit of a cartophile - I've got 2 shelves devoted to them at the moment. I have a version of the StevieruleTM which goes 'No Map no Trip'. OS maps now cover the whole of the UK at 1:25000 and are so much clearer than the 1:50000, which I use mostly for cycling. I still love the 1 inch tourist maps with the colouring & hachuring but you can't beat the large scale for navigating in mist/cloud. Also you get spoilt by the quality of orienteering maps 1:10000 or 1:15000 using specialised software, where you can navigate to the nearest 10 metres.
I have inherited dozens of OS maps from my cartophilic Dad, mostly 6th Edition but some older than that (pre-war). The expansion of some towns is phenomenal. Crawley, for example, was a compact place with a station and a high street but is now a vast, amorphous sprawl. The new 1:50,000 and 1:25,000 maps are more accurate and detailed than their older counterparts, particularly in regard of contours. There are sad (old meaning) bits such as "Course of old railway" and "Mines (disused)" (Yeah, so's mine). Even though the OS Grid has always been metric I'll never get used to heights in metres. My house is at 557 ft, not 169 metres, so I claim the title of Highest-living Morniverser. [Non-mappies look away NOW] The OS Grid is a Transverse Mercator projection, prime meridian 2°W, based on a model of the Earth developed by Sir George Airy over 100 years ago. It's a tiny bit different from modern values both in size and degree of flattening. There is a scale reduction of 0.04%, presumably to allow for the expansion of the scale in the projection away from the prime meridian.
[Rosie] I cannot claim such a lofty domicile, but two minutes' drive gently uphill takes me to this point, Cossham Hospital, the highest point in Bristol at 369 feet (112 meters). On a clear day the views over the city, the Severn Valley, Forest of Dean and even the Brecons are excellent. Oh, and thanks for the techie stuff!
[ImNotJohn & Bigsmith] Blimey. We used to use the old red cover jobs when I was doing it, though admitedly I was less than serious about orienteering and probably just ran with an amateur crowd. I had no idea there was a 1:25 000 series of maps available commercially. Do they cover the entire UK? The only 1:50 000 OS map I can reliably put my hand on today would be "Land's End and The Lizard", and I can't for the life of me remember why I bought that one. I used a couple of Welsh ones until they fell apart but Land's End? When did I go there? It has some touristy annotations on it, like scenic photography overlooks and so forth, which my Welsh ones didn't. I suspect it was a detail added halfway through the print run or something. [Rosie] That's a nice legacy you have. I didn't remember that the 1 Inch to 1 Mile series had a metric grid. I do remember that we were taught to read an OS map in Geography class when I was around 11 or 12. That's when I fell in love with the things.