I visited my cousin in Emberton yesterday and we had a stroll around the country park. The river Great Ouse ouses past a reasonnable-sized lake, which is probably a flooded gravel pit.
There are otters there - a mother and two kitts. Cousin showed me a video she took of two of them, waliking across the ice late last November. Naturally, we didn's see any, other than on her video. Exciting stuff! I've never seen otters outside the Scottish islands (Mull, Benbecula and Scalpay).