A pretty definative answer!
I emailed Bill Eltham, an outstation engineer who certified all BOAC, EAA, BCAL, Ghana and Malawi.Standards and Supers, 28 years ago.
He has replied with a pretty fantastic insight into the "tail supports"
The pictures he is refering to are the ones in the earlier post, and some from airliners.net.
The old girl doesn’t seem like a VC10 in these flash BA colours.
She looked regal in the days of BOAC when turned out from a major overhaul and especially on outstations. The royal blue of the 60’s and 70’s made a statement at Rio and Nairobi that’s for sure.
Airplanes come complete from the manufacturers with a list of optional extras just like cameras, cars etc. and one of these was the tail steady.
It was a rather superfluous piece of blacksmithing which on the station where I served was non existent.
High profile companies e.g. BA, PAA, and TWA bought that sort of artillery to cut the excess on insurance policies. They had lots of staff at every station and if critical work was being performed on an engine say, then one doesn’t want the tail wagging. This is provided other operations are not in progress that may conflict with the steady’s purpose as explained in the next paragraph. Its position was at the aft fuselage bulkhead frame if I remember rightly.
Even had there been one I had no time with EAA and BCAL on short turnarounds to drag it to the plane and position it. As the fuel goes on, the tail comes down. As the pax get off, the tail goes up. Catering, cargo and baggage have the same effect. High winds make her bounce about as do the cleaners and the size 14 footed traffic walla leaping up the steps 3 at a time and dumping himself in the forward doorway with his always last minute load sheet.
One would need a man continually winding the steady up and down.
I wonder if the transits you filmed in Africa had the steady under the tail just in case. Then I would ask, In case of what. Maybe as a special one off time when the A/C had a big chunk of rear freight to off/on load such as a cast iron London Public Telephone Box, well perhaps. I had one but no steady so we had all the passengers move to the forward cabin for a glass of champagne whilst my 12 Cariocas at Rio humped it out of the hold.
You wouldn’t believe me if I told that in the middle of the operation the phone inside the box rang and the chief steward said ”hurry up! We’re running out of champagne!” No? I don’t blame you.
Many VC10’s were fitted with top cabin freight doors and did wave about a bit during unloading but I never saw a steady used. I cannot make out a cabin freight door (which were fitted to the left upper fuselage) in the pictures
How about loading 36 tons of concrete aggregate by hand in 1 cwt cans? This is true in Kano, Nigeria but I never had a steady and dare say would have laughed had one been offered.
Were the shots you sent taken as publicity shots? If so, the station engineer may have at last found a use for a steady.
The shot in Addis Ababa may not be a steady but rather a high step ladder for turbine inspection down the flu pipe.
The 2 in Blantyre could be the undercarriage radial arm and the front brace of the pax steps behind it combining to look very much like a steady.
The Kilimanjaro is quite clear and is indeed a steady. The question is Why? Look at the power truck hanging on the rear of the tractor. It does not appear to be connected to the aircraft which indicates to me that this flight is perhaps a layover for more than the transitory 45 minutes.
With a lot of indigenous staff floating about as the picture illustrates, the Stn Eng has put the steady under the tail fuselage but I don’t think it’s actually touching the airframe.
There’s a baggage trolley at the rear cargo door with no activity. A side shot of the hold door would probably show a couple of baggage labourers resting out of the sun until the flight handling winds up.
Is that fuel bowser connected? I don’t think so. There is a Wehenchi (Kenyan Citizen) on the refuelling steps adjacent to the bowser.
In summary, This A/C will be firing up at any time within an hour or two of this photograph being taken.
Finally, there is another piece of ancillary equimnment called a tail strut which was often used by BA on Boeing 707’s but seldom on the 10. This was an altogether different kettle of fist to the steady and used solely for cargo handling.
Then there was the Tail jack used in major overhauls and undercarriage heavy maintenance and weighing. During a full lifting cycle, the aircraft C of G transfers forward to a point where the weight leaves the front jack and rests on the tail jack. A touchy little point that more than one engineer has come unstuck on.
Regards to you in your research. This is the best I can remember from 28 years ago. You may forward this to the web site if you are satisfied and/or feel inclined.
Sincerely, Bill Eltham
The Tail support, copied from the book “Before. Before”
It's often asked, Why doesn't an aeroplane tip up with all those people on it? Or cargo on it?" as the case may be.
Here's an explanation in layman terms for safe cargo handling on a Boeing 707. (VC 10 similar scenario)
We tied tractors to the nose wheels of Britannias and CL 44’s
There are a maximum of 13 pallets which can fit into the fuselage of a B707. They are preloaded with up to 36 tonnes of freight spread evenly over the 13. The fuselage cargo door is set one pallet length back from the forward bulkhead on the left side of the fuselage. This obliges the handlers to off-load the no 2 pallet first, followed by No 3, then 4 etc. This ensures that No 1 is always there to act as a counter balance of cargo in the forward most position from the balance point or fulcrum if you prefer to stop the plane sitting down on its bottom. Believe me it's been done so often.
It's great to know this in case you ever have reason to unload a B 707 without a handbook.
Every time a pallet comes off, all the others in the train must be dragged forward, one at a time, and locked to the floor rails.
If we don't move 'em forward she'll go arse down and now the problem is the remaining pallets have to be dragged up hill toward the doorway until she levels out again by the weight transferring forward. Stay with me please.
If we don't lock 'em down to the tracks each time we move one and the plane does a see-saw with all this movement, the unlocked pallets plus tons of cargo go walkabout and can career back down the track exiting the fuselage by a non existent doorway, taking a large chunk of the aircraft with it.
BCAL usually sent a Loadmaster with each freighter and it was his or her (Yes we had a female loadmaster) job to ensure this didn't happen. It still happened!
Some companies took to carrying this big adjustable strut, of the type which Ed said he’d send me, at all times on all cargo B707 planes in the belly hold to be fitted before pallet handling commenced but think of the weight penalty involved.
Finally, with only pallet No 1 and its load remaining, the aircraft is stabilised in a nose heavy attitude ready to have that first pallet off-loaded.
Ha, caught ya. I don't know sneaking off to get extra help!! 
When I was a boy in the ATC, I remember we used to need pretty good eye sight. Now your telling me your allowed to captain 10's blind 
.... I know the boys at Whiehall are cutting back.... but maybe its time for another medical! 
. I remember these tail props very well, they were mainly used in third world countries (such as Lancashire). But nobody ever seemed to mention them (or take photos of them, apparently). Whilst searching for photos of them, as evidence of their existence, I discovered that they weren't used as much as I remembered. Ah well, that's old age for you 
