RAF Intell Summary
The RAF Intelligence Summary for 30th June states:
4th Squadron AFC moved from CLAIRMARAIS to RECLINGHEM on transfer from
2nd Brigade to 10th Brigade.
Halley's excellent "Squadons of the RAF and Commonwealth 1918-1988" has 4th AFC located at (dates are arrival dates):
Bruay 19 Jan 1918
Claimarais 28 April 1918
Reclinghem 30 June
Not much clarity to your problem since it does not specify north or south, but it does confirm the dates the unit moved.