Course you can Steve

There are lots of companies around who can do this for you. You need two services - "number porting" and "remote call forwarding".
You would need to contact a telecoms firm to provide the service for you, such as
http://www.callsuretelecom.co.uk/ (I use this one, they are pretty good but I'm sure there are plenty others out there)
You'll get some paperwork from them. Inform your current provider you wish to port your number, and get the forms filled out. You'll need to provide the number you wish the calls to be forwarded to (e.g. your new landline number)
Normally takes a week or two for the number to port over (you current provider may drag their heels)
I think the porting costs a one-off £20 and the remote call forwarding £4 a month. You're charged per minute for the forwarded calls obviously, but the rates are very reasonable. Well worth it.
It can be a little bit of a faff to get this set up, but once you're set up that's it, forget about it
