Assuming that the picture shows a top down view of the back of the cab and coal bunker of a tank locomotive, then the two features that stand out are the raised lip along the back of the cab roof and the row of rivets either side of the metal seam in the cab roof, which, using the handly placed ruler, are about 1.10m from the back of the cab. This distance is almost the same as the trailing wheel diameter of the Wainwright H (of 3 ft 7 in).
This picture (linked below) shows the only preserved Wainwright H, no. 263, with the raised roof lip and a roof seam the same distance from the back of the cab as the diameter of the trailing wheels, so I will go with the Wainwright H. But how and when will Hornby tell us for sure, though, Graham?
https://nick86235.smugmug.com/Trains/2013/Spring-2013/i-cDBwKfN/0/XL/20130328_15-XL.jpg