Help to identify a mystery ladder

This ladder (or actually two of them joined together with a bit of angle iron) has been given to the Jet Age Museum. A gentleman we met while fundraising at Tesco had been given it along with the story that it had come from an ‘aeroplane that Churchill had flown in.’ Each half measures about 5 ft in length, hinged roughly in the middle. Any thoughts?

He also gave us a fascinating set of diaries of an R W Walker dating from 1941-1943 that record the day to day activities at GAC including details of meetings, visits and telephone calls. Much of the E28/39 development and testing is referred to. The handwriting is very small and there are lots of abbreviations which will require some deciphering but its a unique resource.