Old Dinkys were generally scaled a bit bigger than Corgis of the same era but there were discrepancies within the brands too. The red Mercedes is a Dinky, the blue a Corgi. (I've chosen extreme examples to illustrate the point.)
And Dinkys were generally a bit smaller than 1.43 scale. Here I've placed a Dinky Herald behind a modern-day Vanguards model, which is true 1.43, or very close to it.
I just received this new IXO Opel Kapitän and, although it's a great looking model for the price, it's way too big. It should be the same length as the true 1.43 Vanguards Vauxhall above it.