That looks like it could be an old supply pipe. It's capped, has a shut off valve and is right next to the meter so might have been the pipe that used to supply gas into the meter, although it's been replaced by the pipe next to it.

The question is, does it contain gas or has it been disconnected at the other end (where it connects to the gas main, under the road)? Your gas network company should be able to tell you but I think they will need to come out and check. They will take the cap off an open the valve to find out then will seal it up again. If it is still connected then you need the gas network company to remove it. This could cost a lot. If it is not connected then I'm not sure who is responsible for it. The gas network company should be able to tell you.

I've just googled and it could be an old town gas pipe which was replaced when we swapped to natural gas. If you ask your gas network company for a safety check on it they should check it for free.

Yeah, that would make sense to me as well. In theory, if it’s some old town gas pipe then it should have been drained completely by now. In theory, a gas safe engineer might be able to help with removal if the pipe is completely dead, but I’d have to try and do some research to be sure. But I agree with the above - your gas transporter can almost certainly figure this sort of thing out. :)

Hi, I bought a property (old garage) 5 years ago and we are converting it into a house. There is a gas main ghat comes through the basement wall but there is no meter. The Cadent guys have been out and said that it is filled with a paste and that it is still live, although it must be over 20 years since it has been connected to a boiler of any kind. There is no meter on site so it must have been removed by British Gas and the pipe sealed up, but there is still gas pressure in the pipe according to Cadent surveyors. 
I don’t want gas in the property when we have completed the refurb and I need to box in the old gas main as we are tanking the basement, so my question is, do I have to pay for this main to be removed or is it the responsibility of Cadent to remove it or at least for them to ensure that there is no mains pressure gas in the pipe? 

Only your gas network operator (Cadent) can remove the pipe. If they decide to remove it there will be no charge. If you request it I think there's a charge. There's a "disconnections" page on their website with the details, including a guide to the costs.

Just to add to that…

If you think you might ever use gas again someday, the best advice would be to leave the supply pipes in place to facilitate much easier reconnection.

However, if you know that you will NEVER use gas again AND you are absolutely sure that you won’t ever use gas again, my advice would generally lean towards permanent removal for safety reasons - it’s then one less thing to go kaboom in the property and completely eliminates the risk of a gas leak.

If the meter is already gone (which it sounds like it is in your case) then https://cadentgas.com/services/household-customer/disconnections should get you started.

It’s quicker to apply online, but they do take phone requests as well via their Connections Team on 0800 0745 788. You won’t be committed to paying a penny unless you actually want to go ahead with disconnection. Cadent wishes to inform you that their disconnection service may cost up to £4,000 and the gas meter must be removed before they can remove the supply pipe.

If you go ahead with the job, they’ll take care of removing the entire supply pipework. deal with the paperwork and most likely terminating the MPRN if needed.

If you decide not to accept the quote within 90 days, the job won’t go ahead and you won’t be charged.

Thank you so much for taking the effort to send me such a detailed response, much appreciated. 
my issue with the process is that there is no MPRN as there isn’t a meter and there hasn’t been for over a decade. This is in effect a dead supply and should have been properly (and safely) disconnected years ago. The issue is that Cadent are trying to charge me to remove a pipe that wasn’t correctly disconnected by British Gas when the meter was removed. 
Cadent are sending an engineer out to look at the pipe and advise on cost (if there is a cost). 

You’re welcome.

If there’s no MPRN anymore, then that only serves to make things a little bit easier. That would immediately satisfy Cadent that the gas meter is gone and there’s no active gas service currently in use which makes paperwork faster.

In some ways, if Cadent are planning to upgrade the supply pipes in your area to those new plastic ones… I wonder if they could cut you a deal? Something like making it so that rather than removing and replacing your supply pipes during the upgrade, they just remove them and not bother putting new ones in. I wonder if that could work…?

Perhaps… They could offer a discount for it maybe?

Thanks again and yes let’s hope that when the surveyor comes out and sees that there is no meter and there hasn’t been a supply in decades, that he agrees to simply cutting off the supply safely. 

Interestingly, I've just received a letter from our gas network operator, SGN, telling me that they want to disconnect our supply at the road. Our meter was removed a year ago. They quote the Gas Safety (Installation & use) Regulations 1998 saying that this requires them to disconnect the supply after 12 months (presumably 12 months from the meter being removed). It might be worth checking these regulations and seeing if you can persuade Cadent that they have a responsibility to remove the pipe.

Hi and thank you very much for the feedback that might end being really useful .