Just thought I'd respond to a couple of people who have asked why their favourite hill or hills don't appear in the British Hills app. First of all, I don't create the lists, I use the database created by Graham Jackson, Chris Crocker et al at http://www.biber.fsnet.co.uk.
This database is made up of a combination of Hill Lists. These lists are based around classifications of hills, not hill ranges. So you'll see Munros, Marilyns etc (the definitions are explained in the app). You won't see hill ranges such as Cheviots, Chilterns, Grampians etc - but the hills are probably there.
Secondly I only include the most used hill lists as classifiers - so you won't see a button for "HuMPs" etc. You may still see hills that don't belong to the main groups if you look at nearby hills or hills near another hill on the map. Hope that clears things up.