Food for thought, thanks guys. I am about to do the deed and see what happens. I can't put my PC in to the master socket as it's not really close enough to it, also I have two separate telephone numbers on one BT line, so it will be interesting to see what works when I have finished in view of my limited knowledge.
Update. IT ALL WORKS. Even both numbers ring, what the reception is like, don't know yet. Wow it's so quick. Thanks again folks.