72 mk1 stock on bakerloo?

There's three complete trains on the Bakerloo, plus a three-car, plus a four car half MkI and half MkII. All combined make units 3264-3267 and 3564-3567.

The former Northern Line units do have the charcoal interior panels in place but have brown grab rails and seat dividers.

The former mk1 cars are

3264-4264-4364-3364 (ex 3203-4203-4303-3303)
3464-4564-3564 (ex 3401-4501-3501)

3265-4265-4365-3365 (ex 3218-4218-4318-3318)
3465-4565-3565 (ex 3407-4507-3507)

3267-4267-4367-3367 (ex 3210-4210-4310-3310)
3467-4567-3567 (ex 3412-4512-3512)

Also
3466-4566-3566 (ex 3424-4524-3524)
3266-4266 (ex 4324-3324 turned and converted to A end)

To fill in the blanks 4366-3366 renumbered from existing Mk2 cars 4349-3349 and 3299-4299-4399-3399 renumbered from existing Mk2 cars 3357-4357-4257 and 3439 by turning the former middle motor 3357 into A end driving motor 3299 and former UNDM 3439 into 3399.

The 1972 stock runs in a 7 car formation
(A)DM-T-T-DM+UNDM-T-DM(D)
DM- driving motor
T - trailer
UNDM - uncoupling non driving motor

On the Bakerloo the A end faces south and the D end faces north to simply coupling at Stonebridge Park depot - basically the 33XX middle motor still has its main traction brake control (TBC) which is preferred to the small shunting controls in the cabinet at the end of the UNDM.

One big difference with the 72mk1 is the doors have been replaced from bottom rollers to top hung doors, the window seals are rubber on these cars.

Wasn't the MK1 also Driver and Guard?

Both versions were crew operated when introduced.

The story of the 1972 stock goes back to 1969, when a long-term dispute at Acton Works caused a shortage of air compressors for 1938 stock. This caused serious issues for the Northern line with up to 40 trains each day cancelled and a number of trains short formed with 6 cars rather than seven. Horace Cutler (later to become leader of the GLC) took a rush-hour trip on the line in May 1970 to see how bad it was for himself, and on his return to County Hall there was a bit of an uproar. This resulted in LT ordering 30 trains of 1972 (Mark 1) Stock in July 1970. Due to the urgency of the order a number of features from 1967 stock were retained, including the lack of side doors to the cab.

However, there was then a problem at Metro-Cammell as there was no work available for them from the end of the 1972 Stock order and the start of manufacture of 1973 Stock, which was going to be a bit longer based on the fact that they were of a new design. To keep Metro-Cammell afloat LT then ordered a further 33 trains of 1972 Mark 2 stock, the idea being that they would go immediately to the Northern line to allow some 1938 Stock to be scrapped before the 1956/59 Stock was available, which would happen when they were displaced from the Piccadilly by the 1973 Stock.

It also meant that they could supply the Jubilee line with it's own new(ish) fleet when it opened in 1977 (as planned), as by then enough 1973 Stock would be available to free up the last of the 1959s on the Piccadilly, and then when the Jubilee line gained its own purpose built fleet (which was then supposed to be 1978 Tube Stock, but eventually arrived as 1983 Stock) they could go to the Bakerloo giving it a modern fleet to replace 1938 stock there.

As Jackson and Croome wrote: Who could resist spending a little more public money to achieve such eminently desirable ends?

What actually happened was that 1983 Stock displaced 1972 Mark 2 stock back to the Northern line and 1959 stock from the Northern to the Bakerloo enabling the elimination of 1938 Stock from the Bakerloo... but then the desire came to convert the Bakerloo line to One Person Operation (no doubt assuming that this would be achievable without new trains, unlike on the Northern line). This meant that the 1959s on the Bakerloo were swapped with 1972 Mark 2 stock, which were then converted for OPO.

For the rest of the story I would recommend the February 2020 edition of Underground News, which gives more detail of what went where and when.

They did indeed, 1977-1979.

I seem to recall they had red doors???

It is now a requirement that doors are in a contrasting colour. Could this have been an early experiment in that direction? In the early days, when both Mark 1s and mark 2s ran on the same (Northern) Line it did make it easy to tell them apart, but whether there was any operational advantage in being able to do so?

The story I heard back in the day just a few years after the trains were built was that the Mk2's doors were painted to deal with a poor surface appearance of them when unpainted.  And something about a different supplier or different material/construction compared with 67s and 72Mk1s.
But it could have been experimentation in visual contrast as postulated, or an early toe in the water of a new livery I suppose. I thought they looked quite good like that.

I was there at the time and t697 is on the right lines. Two decisions made for different reasons came together.

The 1972 mk11 was delivered with red doors.

The first decision was that the design gurus decreed that painting the directed would help people with visual impairment to identify the doorways......an early precursor to the contrast requirements in the Rail Vehicle Accessibility Regulations by about 20 years.

The second decision was made a couple of years earlier. All post war tube stock had doors that were cast (pouring molten metal into a door shaped mould). These were comparatively heavy. With the desire to use top hung doors on the mk11, it was thought useful to reduce door mass (a general benefit in any case) and a change to a fabricated construction (aluminium sections and sheet welded together) was implemented.

During manufacture, it proved to be hard to get the brushed aluminium finish to look right; signs of welding remained visible. Thus the decision to paint the doors came as a considerable relief!

I always thought it ironic. Aluminium cars were brought it to save weight, and thus reduce power requirements. Sadly the graffiti scum changed all that. And has been said the finish never weathered. RM664 is another classic example. I used to know someone who worked at Acton, sadly he's no longer with us, and he made the comment: "Looks like LT have found some weightless paint."

I seem to recall the traction equipments on Mk1s having imperial threads and metric on Mk2s, leading to all sorts of troubles when both were on the same line...

And indeed the paint left in the brushes or wasted in spray that missed the car. Was it mostly brush painting at that time?