How does one go about installing a built-in gas oven with an built-in
inset gas hob in the worktop above it in a compliant way?

The Gas Safety Regulations seem to imply that both the oven and the hob
must have fixed pipework. The only possible way I can think of doing
this would be to connect the oven first (access through the hole in the
worktop above - dead easy) then attach enough fixed pipework to the hob
itself for it to be lowered down and somehow threaded around the units
and the oven to meet up with an isolation valve somewhere accessible (in
the void below the oven perhaps).

Is this potentially very awkward/impossible procedure the only way to do
it without the use of a (now apparently non-compliant) flexible hose for
either appliance?
--
Chris Cowley