Peter, as I read it, Alan was referring to an engine/prop arrangement such as the SARO Princess rather than the Shack's Griffon:
The Princess was powered by ten Bristol Proteus turboprop engines, powering six propellers. The four inner propellers were double, contra-rotating propellers driven by a twin version of the Proteus, the Bristol Coupled Proteus; each engine drove one of the propellers. The two outer propellers were single and powered by single engines
From
Wikipedia.
I think the Brabazon had a similar arrangement driven by Centauruses?
Any others?