Thanks & more thanks.
Took on board all you said and decided to check (change) the Hozelock connector just before the pump and “what do you know,, water flow”.
The connecter did seem to have a lot of play in it, so I guess as you said, the pump stooped sucking and air leaked in due to the water being sucked back into the tank (siphon action I think).
Any way, as they say, “Air Today, Gone Tomorrow”.
Yes I had a better day.
Thanks everyone.