Confidence: I'm as sure as I can be.
Notes: Olive-green in colour with occasional small lumps on skin. Body about 4-5cm long, with legs tucked under body. Positioned in a few mm of water, partially hidden by grass stems, at the edge of a puddle, with several ribbons of spawn nearby in slightly deeper water. Spawn had 2 lines of small black eggs. Puddle was about 3m fom a narrow footbridge over fast-flowing brook (Afon Tafell).