Turns out you can put a lat/long into Google maps. You need to use the following format: http://maps.google.com/?sll=53.616%2C-002.816
sll tells Google it is Lat/long, and then you enter it with xx.xxx,yy.yyy format, same as usual. (%2C is the URL safe version of a comma)
When you press go, you will see a map of your grid reference location.