Complex sentence: Amongst the measures implemented were improvised armoured cars and pillboxes facing inwards towards the runways, however rather than training all airmen as infantry on the German model, the RAF created instead the RAF Regiment.
Split into simpler sentences: Amongst the measures implemented were improvised armoured cars and pillboxes facing inwards towards the runways. However, rather than training all airmen as infantry on the German model, the RAF created instead the RAF Regiment.