but as far as I can see there is nothing on the machine to indicate which
inlet is for the hot water and which for the cold.

Get a 'Y' piece and plumb it up cold fill only. Modern ecologically friendly
machines use hardly any water. By the time it has used up the cold lying in
the pipe and drawn any hot water (and it will only even try on 60C+ washes),
it is full and has to heat the cold up using its element anyway. Many
manufacturer's have abandoned the hot fill concept because of this and only
supply a cold fill (and save on the valve and fittings).

Christian.