As far as I know, probably the IWC Mk 11 B.O.A.C had a Bonklip bracelet just as the military RAF and RAAF variants. I got this information from a UK navigator who worked first for RAF and later as a navigator instructor for B.O.A.C. From B.O.A.C there are no documents left about this watch, nor in their archives or the B.O.A.C. museum. There are also few B.O.A.C. pilots and navigators alive to confirm. Please see the article : The B.O.A.C. IWC Mark 11 Wristwatch by Adrian v d Meijden and David SEYFFER, published in Horological Journal February 2016, pp 77-81.
Adrian
(alwaysiwc).