Loadstar, your comments regarding the Massey Harris model numbers has made me realise the 745 model tractors were from Great Britain, I had assumed they were from Canada.
A bit of research shows they were fitted with Perkins L4 diesel engines.
I had no idea Massey had a Perkins connection with that series of tractors. Here in North America they used the Continental diesel or gas engines. Not til the Ferguson alliance did they show up with a Perkins diesel option. Like this little model 50 from a 1958 ad. No more mention of Massey Harris from then on.
Loadstar, a bit more research using 'A World-Wide guide to Massey-Harris, Ferguson and early Massey Ferguson Tractors' by John Farnworth.
In this book the tractors are grouped by country of manufacture. It shows the MH 745, a 745S and a 744PD as being built in UK at Kilmarnock, Scotland.
The 745 and 745S are shown as being powered by a Perkins L4 diesel engine developing 54hp. The 744PD was powered by a Perkins P6 diesel engine developing 42hp.
There are no dates shown for these tractors but as the ad for the 745 in Australia was in the 1950s, my assumption is they were produced after WW2. All other models of MH tractors sold in UK were imported in knock down form and fitted with local wheels, tyres etc.
Another thing I found interesting from this book is that of the tractors produced in North America, only the MH Pony was built in Canada and all other models built in USA. As MH was a Canadian company, I had just assumed most tractors were manufactured in Canada.