[poliss]

Looks like a repainted Hornby Dublo Mallard to me. If all the Wrenn mechanisims were the same as shown on this website http://www.wrennrailways.org.uk/motor.htm then it's not Wrenn. The Hornby Dublo motor is shown here http://tinyurl.com/5rger6
The body looks identical to this Hornby Dublo Sir Nigel Gresley http://tinyurl.com/5tzrzu