I'll get straight to the point.

Does anyone know if the lock part of a mk2 (the part the key goes into, is it known as the barrel?) can be swapped and changed between different door handles?

Yes they can.

If you take a handle out, at the opposite end of the barrel you'll see a 'V' shaped piece of metal with a screw holding it in. With the key in the barrel, undo the screw, take off the metal part and the spring behind it then if you carefully pull on the key the barrel should come out.

Thankyou for the incredibly quick reply, I will try that out. Just to clarify that will allow me to take the locking parts out of some scuzzy handles and put them into some nice handles, so I continue to use the same keys. Is that correct?

Edited 2 October, 201510 yr by Saint Jimi