I was reading through this hoping for more insight from Jack (Hot Water) as he knows the inside of steam preservation better than anyone else here.
As for the comments on why a new T1 should go for the Mallard record, why not? I agree with the others who have supposed it would be tough (if not impossible) to get permission to use the tracks where any non-company-owned loco would be allowed to go anywhere near that fast, steam or diesel.
Please, let's keep the rumors out of this discussion of all the other locos that "supposedly" went faster than Mallard's 1938 record. For years, I've heard of rumors of PRR, MILW and NYC locos going faster than this, none ever supported by data and all 'unofficial' runs just to see if they could do it.
As far as I know, the 1936 run of a German 4-6-4 is argued by many German historians as the true record holder (at just shy of 125 MPH), in that their run was on level track, not downhill as Mallard's run was, and that the German loco was just fine after that run; Mallard, as far as I've read, needed a lot of work after limping away from a run which caused a lot of problems for the locomotive.
There were plans, I've read, for a run at 130MPH (a speed which the crew later said could have been met in '38 if Mallard hadn't had to slow down for a couple of junctions along the run) in 1939 with another A4 Pacific, but we all know where the focus for the empire was by the fall of that year.
I haven't read much on the T-1s, but several knowledgeable steam folks aren't calling BS on the possibility, so to me this suggests it was technically possible for a T1 to have gone that fast. I doubt it ever did, from what I've read.
All this said, as others have pointed out there are few places you could go that fast in the US for any appreciable distance. Would any of them let a steam locomotive go for the record? Sure, UK's Tornado recently broke 100MPH on a mainline, but that run was made at night, with very little fanfare until it had accomplished the task.
Let's not forget that nobody ever made a serious attempt to go that fast with steam ever again in any official capacity. I can't help but think there might be a reason for that.
