The law's now changed (as of Apr 2016)... All dogs in England, Wales, Scotland and Northern Ireland must be micro-chipped. . This will normally set you back around £20 at your local vets.
The good people at the Dogs Trust, are running a free chipping service. Locations can be found via the link.
Please donate anything you can, to help keep this charity running.
I've put this in Deals, as free over £20 is a deal in my eyes.
My apologies if this has been posted before. I did search but couldn't find anything.
I did see this somewhere else, and thought it would be good to post here. So a thanks to the original poster.