Bob,
I'm almost certain you need to be thinking of Hampshire, UK - not New Hampshire, USA. Widen your horizons. Look far over the horizon.
I don't think it would be a simple "Let's drop by for a tea/coffee." That would make quite a drive... if you survive the water hazard.
Richard
You are right that the 1 hole water pumps aren't the easiest things to find. A very cursory check of some of the restoration parts suppliers in the US didn't turn up anyone selling rebuilt or replacement units. Depending on whether you have a pump housing and its condition, a rebuild kit like this one
https://www.ebay.com/itm/28537853067...3ABFBMsOn6pJpj might help you.