On a similar topic, how was the inside cylinder on No. 2001 set up? Was it offset by 7 degrees like Gresley's pacifics? Was there a set of Lenz between the frames or were the valve movements derived from the outside valves? Gresley's conjugated valve gear didn't work with poppet valves did it? I ask only because if Cock O' The North's exhaust beat was syncopated, a modified A4 sound file would be appropriate. If the beats were regular, then the Duke of Gloucester.