Not sure why such a wayleave would need to be on the deeds - it's a contract between the then owner and the utility company. This would especially apply if the gas supply was installed after the house was built.
You probably want to look at the conveyancing documentation. Did your solicitor ask the vendor a list of questions, and did that list include mention of anything like that ?
When I bought my house, I got a fairly extensive form (standard questionnaire) from the vendor, and one of the questions asks any formal or informal agreement with a third party over the land. This would cover things like the right of a neighbour to use your path to get to his garage, but I'd expect it to include things like services run through the garden. As it happens, there were several false statements in the one I got, but I didn't bother about it as I already knew about them.
So if a previous owner said there were no such agreements in place, yet there was one for the gas pipe, then in theory you'd have a claim against them. In practice that would be difficult to enforce - firstly the 6 year statute of limitations for private action would probably apply, and secondly they may be able to argue they didn't know because a previous owner didn't tell them.