The walks vary in location and some are in London whilst others are in the surrounding area, but never more than a reasonable train ride from the centre.
You can take up to three walks with them for free before you have to join. More committed members can also attend the regular social events and walking weekends away. Walks take place on evenings and weekends, and all are accessible by public transport.
There are, apparently, up to five walks a week to choose from, "with everything from evening strolls through London’s parks to hiking Ben Nevis the hard way".
For more information visit the website at http://www.metropolitan-walkers.org.uk/.