Peter Strange lists 14 5 plank wagons all ex-MR in the WC&PR goods stock but it is clear from the available photos in his book that the sources of these were varied. At least two none MR wagons can been seen in the available photos, including #21 which is most clearly not ex-MR (H/T Compound2632).
Those confirmed to be ex-MR stock from photos include #3,#5, #6 and #7. As best I can tell #3 and at least one other ex-MR 5 plank were D299 with the later Ellis 10A axle-boxes.
The Slaters Kit 4027 provides an easy route to D299 MR 5 plank wagons of the correct vintage and I went ahead on this basis. Construction was straightforward but I fell into the minor trap of the newcomer as the kit has one crucial flaw pointed out by Compound2632 in his Topic on D299. This caused my buffer bars to be placed 0.5mm to high relative to the sole bars but once done there was no undo and it's only obvious to the experienced eye. If I build another I'll know better.
Edited by BWsTrains