Unsure that it should be called the Barlow Wadley, as the
invention was by Dr Wadley alone. Who was Barlow? (Not
the Stratford Johns character in Z Cars, that's for sure!)

Is there any reason that the comb has to be harmonics of1MHz? Could it
be 2MHz it the tunable IF were to be 2 - 4 MHz?

Just a thought, with thanks to the anonymous kindly donor of
the 4-gang 500pF tuning condenser if the CLubman type RX
tuned from 1.8 to 5.4 would give as a first attempt, Top
Band, 80 and 60 amateur bands with a reasonably linear tuning
range of 2 - 4 before HF end scale cramping came into play.

/WAFFLE MODE :-)