Trying to remember my father talking about flying Halifaxs all those years ago.
He said it was very important to lead with an outer engine when opening up in the air, IIRC it was No 4 with Hercules and No1 with Merlins. This was because even with square rudders there was not really sufficient yaw stabilisation to cope with the wrong outer delivering full power before the rest.
A feature of the engines was that the props were in line with the cockpit so engine syncronisation was carried out by ‘ghosting’ the props. The inners were balanced by reference to the radio operators eyeballs and by looking through an inner prop disc one would adjust the outer so that the stroboscopic effect would render the prop apparently stationary.
When flying on three with any outer feathered, quite common with the Hercules oil gulping habits, any increase in power to correct, say on the approach, the inners were ALWAYS brought up before the remaining outer.
An additional problem was carried over to the Meteor. Undercarriage lowering was a hit or miss affair as to which mainwheel went down first. The Messier undercarriage had loads of built in headwinds and could slew the aircraft quite effectively when one led all the way.
The fins where all built the same way to the end. The square ones merely had fairings riveted to the original triangular fins. De Haviland continued with the Vampire T11, the long fin fairings were again riveted over the original fins.