Baker Street track layout.

It would hit the circle at much to steeper angle to be part of it.

There is always a bit of an overrun beyond stopping marks, stops, (buffers) are normally attached to rails and you would not want a train accidentally kissing them to be derailed.

I can't be entirely certain form your description, but it sounds like what you're talking about is the old Chiltern Court coal siding.

The coal to the block of flats above Baker Street was until the '50s supplied directly by rail to a siding beneath the complex, directly opposite and branching off from the track in Baker St P1. I believe every week a wagon would arrive on this siding, the coal would be unloaded, and then the waste ash from the Chiltern Court boilers would be loaded into the wagon to be taken into the country somewhere (Croxley tip rings a bell?) to be disposed of.

For the ancients on here. Hughie Green, of Opportunity Knocks and Double Your Money used to live there and had a model railway in one of the rooms.

The novelists Arnold Bennett and H. G. Wells also lived there.

It also reminded me of the ex BR stations Upney to Upminster Bridge had coal boilers for the radiators later changed to gas. The coal shute cover at Elm Park being in the street just outside the entrance which allowed coal to be dropped into the room below the booking hall.

It always seemed amazing to me that this coal delivery/ash removal could be cost effective and not so disruptive as to be impractical. I imagine the train of loco, wagons, brake van having to arrive in platform 2 or 3, secure, uncouple the loco, run the loco round via crossovers on the Circle and the north end of the station, draw the train north, propel into the siding, blocking platform 1. Then when unloading/loading was complete, draw the brake van north and shunt it to platform 2 or maybe the buffer end of platform 1 if the number of wagons allowed the points to be cleared, then return and draw the wagons north, shunt back on to the brake van before coupling up and the whole train eventually departing north. Was this what was done? And what time of the day was all this done!?

Doubtful as the building is now in private hands.

They have recently split the power supply at 55 Broadway from St James's Park station pending the hotel conversion. I suspect this would have been the same with the sale of Chiltern Court.

When I worked at 55 Broadway the power came from the LT supply. It was not as stable as the national grid and would fluctuate as trains went through the station. The clocks on early computers would not keep time.

This was a long time ago and the supplier confirmed the problem with the manufacturer.

Baker Street 1933 track layout here in great detail if you enlarge it enough!

The comment is from Hughie Green's daughter, (Linda, not the famous one!), who described the electric supply thus. Seemingly, the use of some electrical devices was less than satisfactory as a result of differing supply parameters.
I'm inclined to think that the voltage would have been in the region of 230-250, but at 33⅓ cycles.
Perhaps someone here could help?

Going back to the original question, I had a look at the National Library of Scotland's Georeferenced maps and found that the siding is shown here: maps.nls.uk/geo/explore/#zoom=19&lat=51.52313&lon=-0.15652&layers=173&b=1 (if the link works) diverging part way along platform 1. It's amazing how a wide-ranging and interesting discussion can arise from a straightforward query!

Whatever happened to the siding with signal M14 as its outlet, near the signal box. I didn't realise that there was anything but a solid brickwall there?

So I presume that the loco that brought in the Aylesbury arrival was left in platform 4 when the train departed north, and then worked forward into this loco siding to await the following Aylesbury arrival. It then shunted onto the north end of that later train to take it back north, and so on, and so on, ..... Does that mean that there was a loco with two-man crew each sat for nearly an hour throughout most of each day? Seems most inefficient working! A similar thing happened in the peaks at Liverpool Street bay road, or just outside Aldgate, but Aylesbury trains would have been more frequent at peak time.

It only inefficient if the crew are twiddling their thumbs, if they were released for a break then it's only inefficient for locomotives not crew.

Yes a driver and an assistant.

I think they did not have a deadman’s handle.