Also during the morning, but circa 1921 and a lot further north than Sussex.
On the Swinton & Knottingley NE-MR Joint Line an NER T2 Class 0-8-0 is hauling coal.
There is a newcomer in the ranks though.
The second wagon behind the locomotive is classified Diagram P4, has six side planks and is rated at 10 1/2 Tons, but it is newly built by the private contractor Birmingham Carriage & Wagon.
However, the curved ends are not present in this version of the Diagram P4 and it is a lot younger than most of the other Diagram P4 hoppers in the train.
The single photo of this variant came with builder and date of build, late 1920, no information about how many BC&W built or even why the company was building 10 1/2 Ton hoppers in 1920.
Almost two decades had passed since Gibb, as NER General Manager, had gone to the USA on a visit and came back determined to improve the company's efficiency.
At that time British Railway companies in India were the only ones who recorded ton-mile data but Gibb, despite the derision of other companies began to record that data as part of his reforms.
Other reforms were the introduction of larger capacity wagons drawn by larger locomotives, though the company's first T Class by Wilson Worsdell actually pre-dated Gibb's first ton-mile reports.
The NER had built 15 Ton, 20 Ton, 32 Ton and even 40 Ton bogie hoppers in the wake of Gibb's visit, though the company settled on 20 Tons as the company standard for a two-axle wagon after the British Government Board of Trade Railway Inspectorate approved the 10 tons per axle loading.
That was in the early years of the 20th century, so technically speaking, the 10 1/2, 11, 12, 15 and even 17 Ton examples were obsolete.
So why were "a number" of 10 1/2 Ton hoppers given to BC&W to build in 1920?
I don't know and the following is just my opinion.
First off, some background.
In 1920 the government still controlled the railways throught the Railway Executive Committee, a WWI body.
The railways would not become independent again until 1921, to be almost immediately presented with the passing of the Railways Act, which would force the grouping in to the Big Four in 1923.
However, at least two companies would be "grouped" before then, the Lancashire & Yorkshire being taken over by the LNWR and the Hull & Barnsley being taken over by the NER, both in 1922.
By 1920, a post-war slump in industrial demand was evident, dropping from the furious demands made by global warfare. There was also industrial unrest, with miners striking in protest at condition and wages follwing the return of the coal mines to private control. The 1926 General Strike is famous but there had been trouble for six years prior. I believe that the Railway Executive Committe may well have had a hand in producing a contract for P4 hoppers for BC&W in the interests of keeping the company going. The wagon stock had been used hard during WWI and replacements were likely required.
Why the 10 1/2 Ton P4 though? Again. my opinion. This size was within the capability and capacity of the company to produce without having to invest in new equipment or techniques.
Unfortunately, I believe that, unlike the wagon builder Roberts of Wakefield, BC&W records have been lost. My opinion is that it is unlikely the contract was for less than ten wagons and more likely that it was for at least a hundred of them. The wagon in the maker's works shot is of No. 53193, probably the first of the contract to be built. It is also marked SD for the NER's Southern Division, which essentially was, Yorkshire. Even in 1920, a 10 1/2 Ton wagon would not have been at all unusual at a colliery in Yorkshire, even the largest of them.
Alternatively, No. 53193 was a single sample example built by BC&W to offer to the NER and they replied "A 10 tonner? Why would we want that? Thanks but no thanks!" We, or rather I just don't know the full story.
If you know better, then I'd like to hear about it and please quote your sources as I'd like to read them.