The Vickers Vanguard might not have had the sales success of its predecessor, the Viscount, but a number of the passenger planes had a long career as a result of conversion to the Merchantman freighter configuration. One of these is on display at the Brooklands Museum. Since the cargo door was not an original design feature, the fuselage needed to be reinforced to accommodate the stress redistribution around the door aperture.

Since this was a retrofit, it was far simpler to have the reinforcement on the outside of the fuselage. Looking closely at the example at the museum, you can see the multiple layers of reinforcement to build up the thickness in the areas with the greatest stress increase. There were about ten layers in total with them tapering out as you got further from the opening. This was all prior to the days of finite element analysis so would have involved a lot of hand calculations!