Andrew gurgled happily, sounding much like they
were saying:

One wonders whether it would be acceptable to have it in the boot - if
the boot can be accessed from inside the car by putting down the rear
seats.

AIUI, the test for accessibility is "Can the driver get to it in order to
be wearing it BEFORE getting out of the vehicle?"

Of course, whether you _can_ actually don it whilst still sat behind the
wheel is another question...