They might be right and wrong. The info that I have been able to find is that the 701 as it was designated in the UK was the same as the No 1 baler in the US. A number of engines were offered, one being a Wisconsin. In the UK the Armstrong Siddely 14-22 proved to be the most popular.
I understand that the 14-22 was introduced in 1945 by A-S from their factory in Leicester.
If introduced in 1945 its very unlikely that it would have had much use by the time VE Day arrived.
The Wartime Farm is a very interesting programme and a valuable insight into those times for us who came along later. You will probably have noticed that at the farm gate where the tractors and manure spreader are parked there is I think, a Fordson E27N fitted with halftracks. I have no idea what make they might be but I somehow doubt that they were produced during actual wartime. I'm guessing that they are more early 50's prior to the arrival of the later Major.