The movements trade trains airmen to load plan and complete weight and balance (trims) at the SAC (Movs Controller) level. This trained airman as things stand completes/coordinates all the paperwork (pax/trim/cargo) that is then handed over to the DAMO (Flt Lt/WO runner) who double checks the paperwork (of the airman who has had formal training)who then takes the documents to the loadmaster who double checks the DAMO's checks of the airman who then splits the manifest and cargo docs out from the pile and passes the trim sheet to the captain who then.............
If you work back all the paperwork handling and officialdom into the scenario at the start of this thread you can see why the RAF closes out its flights so early where as a commercial operation is some what more streamlined and efficient.
In civvy street if a passenger is running late for a flight the dispatcher makes a mental note but still runs his documentation/process with the information that is known to him be it pax/cargo/fuel etc - he would normally tell the capt the late runners info BTW. If the pax does rock-up after the paperwork has been printed the dispatcher amends the load/trim sheet by way of a Last Minute Change ammendment, and the pax/bag flies. An LMC can run on average 500-1000 kgs. Instead of getting into a verbal slanging match at check-in, the 'flexible' mover would take the upper hand, put the pax in their place verbally and let them fly. At Brize no pan is more than 15 minutes away and quick call to the pan phone/movers puts those in the know in the loop. Civvy street does this for commercial reasons/passenger retention, I think the Movers need to apply the same methodology/ethics with a pax who has a requirement to be on that jet.
I have worked to a remit of check-in closure at -45mins with an acft turn around time of 90 mins (320 pax off/on, decater/cater, clean, bagsoff/on, crew change, security checks) and this was at a very large airport near Hounslow under the current security restrictions. Interstingly, so long as I had the acft doors closed at the Scheduled Time of Departure then the call as to whether a pax is accepted or not fell not to the acft capt but to me. Yes it was a team effort, but ultimately the on time performance was a function of the ground operation and how I managed the turn around and third party suppliers. If I made the wrong call then the capt had my name and a voyage report was raised and I was held to account and lessons would be learnt if applicable.