Getting back to your gas hob, Hal... there is a little (or maybe, well) known trick among DIYers. If you're confident enough, fit the thing then turn the gas off at the meter and ring Bord Gais to report a smell of gas. They'll send a man out who'll switch it back on for you and check for leaks - with state of the art sensors, not a bottle of soapy water! - all free, gratis and for nothing!