Got to share my vintage Navitimer. Any info greatly appreciated!

[watchthisone2]

Hi All,
Have been looking out for a vintage Navitimer for a while and think I got it sorted. Its a black on black dial and has a serial number from 1955 I think. The interesting thing is that it has no wings on the dial, only a "B" above Breitling and the balance cock has BOW on it rather than the usual WOG. Does anyone know why?
I have also the receipt for a service from 2006, so I am pretty sure it is all genuine....I hope.
Many thanks, hope you like it.