A double Osterley loop? Is that allowed under Merchant's?
I agree, the WPMCC is a finer tournament than the PMCWC as can be seen by the actions of the late Humphrey Lyttleton who, even though classified as a professional (due to appearances on ISIHAC), would not counternance appearing in the PMCWC, preferring to commentate on the WPMCC as it was the pull of the amateur game that enthralled him.
As to a move, if we're not playing Merchant's, Fairlop. If Merchant's, the last move was invalid, but Fairlop is still OK from Goldhawk Road, not as good a move under Merchant's obviously.