Sorry Heatstore. It just has "Boilermate" on the cylinder, no "II" label visible.
I have found a date of installation sticker stating 1991.
You are right, the blue pump does have a BG label and is dated 2006.
Thanks
Our new house came with a Boilermate heatsource system driven by a Potterton Profile boiler. I believe the whole system is 20 years old.
With the central heating on there is absolutely no hot water at the taps. Switch heating off and after an hour to ninety minutes there is piping hot water...