This information is kindly supplied by ARMA:
summary
When it comes to gas safety, ARMA supports and recommends to leaseholders the information provided by Gas Safe Register. Gas Safe Register replaced CORGI as the official gas registration body for the United Kingdom, Isle of Man and Guernsey. By law, all gas engineers must be on the Gas Safe Register.
In this Advice Note, well take a quick look at how you can make sure you stay gas safe in your flat.