I have been informed that this little bee is probably a mining bee of the genus Andrena.
There are approximately 65 different species of these in the UK alone and they are apparently difficult to ID down to this level, so I shall not even attempt to do so. However, if anyone is able to from my photos I would be grateful for the information.
They often dig a nest in lawns or paths, but don’t cause any problems for the lawn. They also have a very weak sting and are non-aggressive.
They are known as solitary bees as they do not live in a colony, although they may nest within close proximity to other solitary bees. They are considered to be more efficient pollinators than honey bees. There is more information about solitary bees here.
Update: The consensus of opinion on Twitter is that this bee is most likely to be Andrena bicolor.