Here’s a useful free App for those of you who have either and iPhone or and Android phone. The OS Locate App https://www.ordnancesurvey.co.uk/shop/os-locate uses the GPS built into your phone to tell you your location which is expressed as an OS Grid Reference (i.e.TL343905). It also has an electronic compass to show the bearing for your direction of travel.
Another useful feature, if you have a telephone signal, is the capability to share information about your location using either SMS text messaging, email, Facebook or Twitter. This could be helpful if assistance is needed in an emergency situation. I’ve installed the App on my phone and it seems to work well.