Perhaps Vne was variable on the Vibrator. Certainly Vno was. I recall from my 'How to Fly The Vanguard' Notes from 100 years ago: Vno = 303 minus altitude (in thousands of feet).
The alternators were 'frequency wild' - this was OK for e.g. anti-icing tail, props & engine intakes. Transformer/ rectifier units & inverters supplied controlled AC & DC.
Cruise speed was also variable - we set the LP RPMs to 12,500 and accepted whatever IAS it gave us. Other power settings: climb 12,500 (IAS 230 kt), max continuous 13,500, ops nec 13,000. In the cruise TAS was in the region of 330-340 kt.
On the approach the props were in the constant speed range so power setting was judged by fuel flow - approx 600 kg/hr/eng IIRC. Every change of power required rudder trim adjustment. If the slip needle was not centred the a/c would tend to pitch down - something to do with tailplane dihedral (contd. p94)