Complex sentence: It provided defence for Northern Scotland, moving to Castletown on 21 August and later to RAF Skeabrae, until May 1942 when it moved South to RAF North Weald, having re-equipped with Spitfires in November 1941.
Split into simpler sentences: It provided defence for Northern Scotland, moving to Castletown on 21 August and later to RAF Skeabrae. In May 1942 it moved south to RAF North Weald, having re-equipped with Spitfires in November 1941.