London walks. Saturday Walkers Club. The OS has just cut the price of digital OS 1:25K mapping by 90% (which says more about how much it used to cost, than how much it costs now).
Why would you want it? If you have a GPS Smartphone/GPS Tablet/Dedicated walkers satnav, then you can have the OS map, overlayed with GPS routes from this or other websites, with a 'you are here', which, especially in lowland (where navigation is harder), is amazingly brilliant. Negatives are : Screen is small so only useful for micro navigation (no big picture), Smartphone/Tablet batteries don't last so long with GPS enabled (a few hours), Dedicated Walkers Satnav batteries lasts all day, but hardware is an additional £200 or so, you are then locked in to hardware provider, and its an extra device to carry around.
Pete's Walks.