RAF Spec P13/36 vs B12/36

[PMN1]

The RAF’s P13/36 specification that led to the Manchester called for an aircraft using two engines in the 2,000hp region however in the book ‘RAF Bomber Command and its aircraft 1936-1940’ by James Goulding and Philip Moyes, it says that there ‘had always been a substantial body of opinion within the Air Staff that favoured the use of four engines in the P13/36 designs but this had been overruled in favour of two engines mainly because a smaller aircraft would result and maintenance problems would be eased’ – has anyone else read this?

The evolution of the Manchester into the Lancaster and the redesign of the HP design to use four engines are well known but what would have been the result if 4 engines had been specified for P13/36 from the start?

What engines types would have been proposed as there is no mention of engine types?

Would the initial design have been closer to Lancaster B.1 and Halifax B.1 size and performance from the outset?

Given the delays to what ended up as the Halifax, caused by changing from two to four engines, would we have seen the Halifax entering service sooner?

What effect would it have had on the B12/36 spec, would it or the P13/36 spec be cancelled in favour of the other (the B12/36 spec had a 14,000-lb bombload vs 8,000-lb for the P13/36 spec but the P13/36 had what turned out to be a better bomb bay layout and structure.

What effect would this have had on the following B1/39 spec (the standard bomber project). This had the same bomb bay layout as the B12/36 designs and would have suffered the same problems had it not been cancelled by Beaverbrook when he was at MAP - the inability to carry (internally at least) anything bigger vthan 2,000lb

[merlin]

The B.12/36 spec yes was for a four-engined 'heavy' bomber. Its disadvantage was that the bomb load specified was for lots of small bombs. Some of the designs had bombs stowed in the wings. The winner of the Specification, after a lot of deliberation was the Short Stirling (initially it was a Bolton Paul design), - it would also have been a Supermarine bomber that that was too badly damaged in the Battle of Britain.
The B.13/36 spec. had an extra bit of unexpected flexibility built into the design, because of the requirement for two 18" torpedoes to be carried. This gave the designs longer bomb bays - which later could accommodate bigger bombs.
Specifying four engines from the start wouldn't IMO have made much difference to the Halifax - the mock up conference was held on the 8th July '37, on the 24th the CAS decided that it should be refitted with four engines - the change over according to Handley Page delayed the prototype by six months - maiden flight 25th Oct '39. But the production order had already been made 7th Jan '38.