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Welcome back Wigan!
You are quite right, BKEW was imported from Germany as opposed to being exported there!
This throws-up an interesting observation in that there are now two or three craft involved with Mann's which seem to have come by way of Deutschland:
Peter Cadbury's D-HMAC which became G-CHOC in 1977
Charles Hughesdon'd D-HJFF which became G-BTWA in 1978
Norman Foster's D-HDAD which became G-BKEW in 1982
I have to admit that I'm not entirely sure as to whether Mann's were involved with HJFF/BTWA (the craft oft chartered by Estepo) for even though Hughesdon kept his craft with Mann's in the 70's it would seem as though he had moved to Hanson's by the early 80's.
Aside perhaps from someone at Mann's having an association with a German dealer one imagines that the number of German imports was simply down to their 206 population which, I am guessing, was one of the largest outside of the UK?
During the 70's Mann's must have sold more single-turbine civilian helicopters in the UK than anyone else and it would be no surprise to discover that they may have needed to supplement their Agusta-stock with craft from elsewhere.
The Alton Towers LongRanger was also an ex-German craft (D-HBBZ) but I think this came in via CSE - Paco would know.