Lots of people on Twitter saying they are SAS planes but this seems unlikely.
Might be on their way to Duxford airshow. The US has had two at Mildenhall since 2013, maybe they just came down to that London for the day for a show and an Angus Steak House? http://www.bbc.co.uk/news/uk-england-suffolk-23469986
Not replacing Chinooks no - here's a highly speculative article which doesn't help much:
http://www.eliteukforces.info/uk-military-news/05042016-osprey-special-forces.php
Lots of people on Twitter saying they are SAS planes but this seems unlikely.
Might be on their way to Duxford airshow. The US has had two at Mildenhall since 2013, maybe they just came down to that London for the day for a show and an Angus Steak House?
http://www.bbc.co.uk/news/uk-england-suffolk-23469986