You see with that extra 55ltrs of fuel I would have absouletly no reason to be over the cairngorms in horrible conditions I would be up the east coast with loads of options.
MJ - on a serious point that is not always possible.
For example you may want to do a trip to the CIs or any other longer sea passage. Climbing high enough to glide to land may not be possible. Yes, of course you could refuse the trip without an extra engine, but then again not everyone has that luxury. Your assessment is that an engine failure is highly unlikely. However you might well take comfort from the chute subject to your assessment of the pros and cons of a water based landing with or without the chute. Unfortunately all the extra fuel in the world is not a substitute nor whatever more advanced skills it is that the pilot may possess.