Yes indeed, those fabric covered wings are a fire waiting to happen. Is it just me (non-aircraft guy) or are these period restored aircraft subject to a higher than average number of problems/crashes/etc.?
Sad to see, but at least it didn't catch the whole aircraft. The Vickers Vimmy at Manchester, back in the late 1970s, was totally destroyed in seconds in a similar incident, caused by ignition of fuel vapour on the fabric.