Have just had a new gas hob installed to replace old one by plumber who is not corgi registered. Do i need to get a corgi registered plumber to check the installation?
You should have had a CORGI register plumber to fit it, from what I've read messing with gas plumbing and not being CORGI registered is an illegal-throw-away-the-key offence.
From the HSE website http://www.hse.gov.uk/gas "By law (a) anyone (whether an employer or self-employed) running a business, e.g. A plumber, who carries out work on a gas appliance/fitting must be CORGI-registered, and (b) any individual doing gas work must be competent to do it safely. DIY gas work could be dangerous and is likely to be illegal." Also look at http://www.corgi-gas-safety.com
Put it this way....if your house bursts into flames or blows up and it's traced back to the hob, insurance won't pay out. Don't laugh...it's happened. Report him to trading standards and Corgi and then pay an engineer to have the work checked out. It's worth it for the peace of mind.