The silver jam sandwich did not make the cut.
MPSA is still 'green' as they work their way through the wiring but the other pair MPSB and C are boring old blue and yellow but incomplete.
In the end I think the wish to be different fell to the obvious. As these three are the aircraft most likely to be despatched to other parts of the UK to assist [as historically the old Bell's 222s used to] they would have to stray into uncontrolled airspace where they would need to be seen by such as the low and fast military.
The Met got away with staying white with two of the three 355N's because they offered little in the way of extra ability to other forces and rarely left controlled airspace [occasional forays into Kent etc] but the 145s will undoubtedly be different.
There is an image of a painted up EC145 G-MPSC on-line... but modesty and forum rules dictate that I cannot say where!