Complex sentence: In October 1943 the Ministry of Information released a film showing workers at the Broughton factory assembling one aircraft (aircraft build number LN514) in a "record" 23 hours 48 minutes, although there was substantial pre-assembly done to make this record time achievable.
Split into simpler sentences: In October 1943 the Ministry of Information released a film showing workers at the Broughton factory assembling one aircraft in 23 hours 48 minutes. This was aircraft build number LN514 and there was substantial pre-assembly done to make this record time achievable.