Re: At least people can take comfort from the fact that ...
More to the point if, at best, a load of debris from the now unserviceable engine spews over the M25 or at worst the aircraft is unable to gain enough height as it all goes pear-shaped then what? Time and time again the theory of what is supposed to happen versus what actually happens in these situations is usually worse.
You will end up with an aircraft crashing in a densely populated area unless the pilots had enough control to ditch in one of the reservoirs.
Whether on the ground of the air it is not a risk that should be taken on a whim.