Thankfully, it didn't happen.

This morning, Ellie commented there was a strong smell of petrol in
the car. I thought it was probably another car in traffic, as it
disappeared as we moved away from the lights, but it persisted.

A quick investigation showed the pipe to the fuel rail was wet where
it passes through the foam sleeve, next to the water hose at the
back of the engine (s2 TurboCT).

I drove the 30 miles from where we were to my usual garage, opened
the bonnet, to find a fine jet of fuel spraying from the pipe, aimed
straight at the turbo.

This did not strike me as a great state of affairs, so I hid for a
while, until the residual pressure died down and everything cooled a
bit.

Replacing the pipe itself was easy enough - both ends are possible
to reach, although the bulkhead end wasn't great. An inspection of
the old pipe showed that it seemed to have chafed against the
jubilee clip on the water hose, and rubbed a small hole. When the
engine was stopped, there was a good inch between the clip and the
fuel pipe, which was thoroughly clipped in.

CHECK THIS ON YOUR XM.....

Turn the jubilee clip so the pipe has no edges to rub on. Adjust the
foam to provide most protection. Make sure the fuel pipe is properly
clipped. I was lucky.