Bill Pegg force landed a Britannia on the Severn estuary mudflats after a catastrophic engine failure and in-flight fire. Details and pictures here:
Britannia Aircraft Preservation Trust - History of G-ALRX - the second Britannia prototype
An interesting footnote to this accident is that Stanley Hooker was onboard. If the outcome had been different, there might have been no Pegasus and no Harrier.