I've just had a side extension built, and that involved knocking down the garage that had the Gas meter on the side. Effectively we moved the Meter about 1.2M towards the front of the property.
We come under West and Wales Utilities, and the initial 'quote' was £1328..
The builder had a gas safe engineer cap off the incoming Gas supply and he dug the Gas Pipe out, luckily it went directly to the front of the property anyway so effectively would just need shortening and putting in a ground box at the front of the extension.
I phoned up WWU and they sent an engineer out to have a look, he spoke with the builder and agreed what simple 'excavation' would be required at the front of the extension, so the builder offered to do that for free, the new quote came through for ~£600.. This is mainly due to the ease of just shortening the existing pipe and fixing in a ground box.
Still a rip-off IMO, the guys came down, it took about 20 minutes to screw the ground box in place, and they just cut the incoming gas main 'live', quickly chucked it in the box and capped it off.. the Guy re-installing the meter then turned up and he took 10 minutes, 5 yapping about the new larger ground boxes (I hate them all, ugly things!) and just connected the meter up and left.. so less than 30 minutes of work for £600..