A "Westcott Snatch" is mainly utilised when EGLL are landing Easterlies. Normally the release point for arrivals from the Enroute to Approach guys is Bovingdon, hence the standard "leave BNN heading 250 etc......". This is due to the interaction with stuff departing Luton and alike that may be in conflict. Should there be nothing to affect this, the Enroute may release the arrival at Westcott, thus allowing the Approach controller to turn and descend it earlier (with respect to the controlled airspace steps out that way...........see the Mike Romeo story for that one
).
Obviously, it's quicker than going all the way to BNN, and can be very helpful in getting stuff in and out of the way, especially if there is traffic coming from Lambourne.
From a drivers point of view, the heads up will be "Leave WCO heading" or issued a heading before BNN. It's not uncommon to be told to fly a higher speed than the normal 250/220 knots (or GLF = "go like f**k"). The heading from Westcott is pretty much going to be your base leg, normally point at a 12ish mile final (traffic permitting of course). And of course you'll be issues with a range as we wouldn't want to rush things stupidly now
