The shortening of SIDs has to do with fuel planning, and has happened at many UK airports this year (Luton, Heathrow, Gatwick, Manchester, Prestwick and probably a few more).
When the flight planning is made the airline has to plan to remain at the initial level for the duration of the SID. Flying heavy at low level is in turn very inefficent. Most SIDs were much longer than the actual level segment was ever going to be, so by shortening the SIDs the airlines could plan for a more realistic portion of low level flight. Thereby reducing the amount of fuel needed.
It's probably a reasonably minor saving per flight, but when you do it for thousands of flights a year the numbers quickly stack up.