Cheap offline smartphone maps

Do you use your smartphone to navigate with when on a walk/hike ?  If so, you might be interested in this source of cheap large-scale offline maps (thus avoiding the need for a 3G signal).

I use it with a nav program called Maverick on my Android and it works very well.  For only £15 (currently) for the whole of the UK it's very good value.

(No relationship with the supplier other than as a satisfied customer).