You could try freezing the pipe,(freezer kit available), cutting and usu push fit stop end,or isolating valve. You will have about 20mins to complete the operation.
Why cant you not shut the water off?
ps have replied to you previous request.
Thank you for your help,
I want to work on the pipe without turning the mains cold water off ?
plumer has been in to relocat a new builer and left the origenal water pip sticking out of the ground with a push stop on it . I must cut this pip down enough to go under ground so I can put carpet.