Problem with new pump: Fixed.
When I went to top-up the pressure this afternoon, I noticed that the gauge was not holding the pressure on the dial although it did pump properly.
I did a quick search and found that it was a common problem but it had a quick and simple fix.
At the bottom of the pump, you unscrew the cap, remove the spring and small plastic nib. Clean the port and stretch the spring a wee bit then re-insert. Problem solved.