"Farewell, Farewell" uses the "Fause Foodrage" tune.

I always assumed Richard Thompson got it from the Sweeney's Men version (since Andy Irvine, then of Sweeney's Men was responsible for the error that led to the confusion).

It seems a happy accident, as I can't imagine Farewell, Farewell sung to any other tune.

Has anyone established which tune was used for the Pentangle version, as requested by the OP? I've never heard their version and don't even know which album it's on (assuming it was issued on an album).