sounds like a dunnock. they're quite common and are ground feeders, but are often overlooked because they're so non-descript. if you google the rspb website they have a good section on identifying birds including photographs.
we started feeding the birds last june and since then have counted no less than 25 varieties of birds in the garden - 25!!! we just live in an ordinary suburban area, surrounded by similar houses and it has amazed us. i put out fat balls, peanuts, sunflower seeds and some kitchen food waste (rspb site tells you what attracts the different birds). we also now have 3 birdbaths for them to bath in and drink from. we are now totally addicted to watching the antics of the birds and found it well worth doing a bit of reading up to find out how to attract them into the garden.