Thanks folks -
I have discussed this with Applied Pumps
UNIT 11, COBNAR WOOD CLOSE, SHEEPBRIDGE INDUSTRIAL ESTATE, CHESTERFIELD, DERBYSHIRE. S41 9RQ            

They sell (et al) the Compac 150 which comes with a float switch but more important an overide manual switch. It needs about an inch to prime in manual , got that much. It pumps down to 3mm ish- mop and bucket territory. And shifts 100+ litres a minute (about 100 "aching muscles - weeks" worth). It musn't run dry, for more than a minute ish, but as long as it is watched - that is a small limitation.

Cost is 160 GBP with hose and shipping (by comparison a good deal). Not my house but if I am called to help - I want one of those! I am ready to underwrite the deal.

They have de-humidifiers on loan from the insurance co. From the first deluge. That produced deeper water inside because I was learning what it needed - even though the outside was not as deep.

You could see it bubbling (seepage) up through the concrete floor this time - despite a membrane.