Continuing with the theme started by Chris today, here is my 'something different' not a cover, but in many respects an item that is much harder to find than most covers, scarce postal history, in my opinion.
British Forces Post Office Registered Packet Receipt (I assume from a duplicated booklet) form P1167B Revd 59358/58, addressed from Div 1 with the address 255 and noted office of posting as 1023 - so FPO 1023 located at Hohne in Germany 30 10 73. To reverse the datestamp Field Post Office 1022 31 OC 73 located at Dusseldorf - so issued at Hohne and received at Dusseldorf prior to airmail back to the UK?
A very nice item - if you look in the box at the top right it states "Date Stamp" and has in manuscript S 130 with the date 3.10.73
This confirms Hohne as the office designation for the FPO at Hohne was FPO S.130.
I think that you are right with your assumption - from Hohne to the Postal Depot at Dusseldorf and then on a flight to the UK.
Mike