Ask yourself this: If the UK is so efficient then why are the Nav charges so high? Why do so many aircraft take lengthy doglegs to shorten UK track mileage to a minimum in order to save Nav charge costs......and ask yourself whether this practice has an effect on the Carbon footprint!
The UK is in fact the second most expensive ANSP for en-route Nav charges, Swizerland actually being the most costly. Quick examples, en-route, the UK is circa 160% more costly than Irish overflight, 23% more than France, 140% more than Portugal.
The cost decision to avoid expensive airspace clearly must be a commercial factor to be considered, but these days is far less of a balancing game than years ago. Going back 15 years or so, annual en-route charges used to be about 2/3rds of the annual fuel bill - yes, big figures! However given the oil price in recent years this balance is clearly now significantly different, and less weight is given to routing based on ANSP costs vs fuel costs.
Charging changed years ago to the 'Great Circle' rule, so is based on GC distance from entry point to exit point within the ANSP's area of responsibility, or airfeld within. I could therefore file say CC outbound to DW - the UK charge would be GC distance CC to the UK boundary. I could however file northbound up to Scotland, turn around and fly back over the MCT and turn to DW and pay exactly the same ATC fee as going direct (as indeed you clearly would in reality!). Always found it a strange, although hugely simplified measurement of charging
30W