We have/had a pond pump that worked in 2/3 inches of water - we used it in our cellar when that flooded due to a blocked stormdrain down the road. It was widely available and took a standard 'hoseclip' fitting (can't remember the name but it's the most popular hose pipe fitting and is bright yellow), managing to pump water up a storey and some 30ft out into the kitchen sink. Couldn't take it the short way out the front and into the gutter as it would have gone straight back into the blocked stormdrain!

Good luck.

If your house is Tudor, you may be able to get some help from your local authority, whichever department is in charge of listed or historical buildings, or from the Environment Agency.

LTS