This might be some useful background information about British tanks IOTL.
For years I've been working on a TL where the UK is able to spend an extra £50 million per annum on defence 1919-39 which is divided between the Army, RN and RAF on the ratio 15:15:20. Where the money comes from has yet to be definitively worked out, at present I'm thinking of an earlier rescheduling/refinancing of the National Debt, with half the money released going to pay for Lloyd-Georges "Land fit for heroes to live in." and the rest into the armed forces.
The TL for the British Army is the least well developed. It was going to use the extra £225 million available over the 15 financial years from 1919-20 to 1933-34 on equipment rather than maintaining a larger standing army. As follows:
- Keeping the Regular Army in the UK up to date so that an Expeditionary Force of one cavalry division (later a mobile division) and 5 infantry divisions plus an independent tank brigade, AA brigades, corps, army and lines of communications troops could be dispatched to the continent within 6 weeks of the order to mobilise;
- The Territorial Army would be provided with training scales of modern equipment. In war this would be used to mobilise 4 TA infantry divisions plus the correct scale of corps, army and LOC troops for a force of that size;
- Keeping the Coast Defences at home and abroad up to date;
- A larger force of Air Defence Troops (later Anti-Aircraft Command) than was maintained IOTL.
The above is roughly the state the British Army should have been in by 31st March 1939 under the "Deficiency Programme" of 1934, which was the first of the British rearmament programmes. However, the allocation of resources was not necessarily in that order. The fear of air attack at that time (The Bomber Will Always Get Through and films like Things To Come) and the pacifist and isolationist sentiments of the Great British Public at the time the War Office is going to find it easier to get the money for Items 3 and 4 out of Parliament than Items 1 and 2.
IOTL the Net Army Estimates for the period 1925-26 to 1933-34 ranged from a maximum of £54.3 million in 1925-26 to £42.8 million in 1932-33 and the average for the 9 years was £48.5 million. The extra £15 million a year increases the total spending on the British Army by 31% over this period.
In practice most of the extra money is spent on Vote 9 of the Army Estimates, which was for Warlike Stores. Within this period the money spent under Vote 9 was divided under 4 headings (A-D) as follows:
- A - Establishments for Research, Experiment and Design, average £683,300 over this period. Unfortunately I didn't do a breakdown of that when I visited the National Army Museum so I don't know the proportion of that which was spent on Tank and AFV research, experiment and design;
- B - Inspection of Warlike Stores, average £451,900 over this period;
- C - Warlike Stores, average £1,876,200 over this period;
- D - Miscellaneous Charges, average £81,000 over this period.
The total for the above produced the Gross Estimate, which was an average of £3,100,000 over this period. From that was deducted the Appropriations-in-Aid under Heading E, which was an average of £765,100 over this period. This produced the Net Estimate, which over the 9 financial years ending 31st March, 1934 was £2.3 million. All the Headings were divided into Sub-Headings, which for Heading C were as follows:
- Guns & Carriages
- Gun Ammunition
- Small Arms
- Small Arm Ammunition
- Horse Transport Vehicles - excluding the RASC, which had its own Vote in the Army Estimates
- Motor Transport Vehicles (Wheeled)
- Motor Transport Vehicles (Tracked and Half Tracked)
- Anti-Gas Equipment
- Searchlight, Signal and Bridging Equipment
- Miscellaneous Warlike Stores
Tanks were under Head C7. The average spent under it over the 9 financial years ending 31st March, 1934 was £435,900 and for the first half of the 1930s was even lower at £333,400. The actual amount spent on the production of tanks was even less than that because Head C7 was for, "Tanks and other mobile machines on continuous or half-tracks, e.g. artillery dragons, tracked infantry transport and self-propelled mountings for artillery, are included in MT (Tracked and half-tracked)."
In my TL Gross spending on Vote 9 is quintupled in the 9 financial years ending 31st March, 1934 to an average of £15.5 million over this period, which leaves about £2.6 million out of the extra £15 million for other Votes. Within Vote 9 the money is spent proportionately over the headings and sub-headings, except for Head B, which might not go up proportionately. Also as the mechanisation of the army is accelerated the increase in the costs of POL for the MT is partially offset by the reduction in the cost of forage for the horses.
IOTL the British Army was able to move a whole division using Mechanical Transport by 1930. ITTL it was able to move all 5 regular infantry divisions by that time.
ITTL the Army bought 5 times as many Dragon artillery tractors and after the requirements of the Regular Royal Artillery was satisfied the surplus was used by the TA and used to provide the 12 divisions ITTL (because 2 were converted to AA divisions in the 1920s instead of the 1930s) with training scales, which could be pooled to mobilise 4 divisions in war. The extra money also allowed it to buy 35 Birch Guns instead of 7, which equipped 2 artillery brigades with a total of 32 guns in 8 batteries (4 batteries per brigade).
IOTL the RTC initial peace establishment of the RTC was 4 tank battalions (one per infantry division, except there were 5 infantry division instead of 4), plus 12 armoured car companies (IIRC 8 were based in India and paid for by the Government of India) and another 8 armoured car companies in the TA converted from redundant Yeomanry regiments. In the late 1920s it was decided to convert 2 horsed cavalry regiments to armoured cars and disband the 4 RTC armoured car companies in the UK and Egypt as compensation. However, the 2 of the ACCs were used to form an under strength tank battalion in Egypt. Therefore at the end of March 1934 there were 5 RTC battalions, 2 cavalry regiments with armoured cars, 20 horsed cavalry regiments in the UK and Egypt, plus 8 armoured car companies in India. The TA had 16 horsed cavalry regiments and 8 armoured car companies. By 1939 the new Royal Armoured Corps had 8 RTR regiments and 18 converted cavalry regiments and there were still 4 horsed cavalry regiments consisting of the 2 Household Cavalry regiments and the 2 most senior line cavalry regiments. The RTC/RTC companies in India were disbanded in the late 1930s and their light tanks transferred to the Indian Army.
ITTL the British Army had enough money to form 20 tank battalions in the 1920s, but instead of forming 16 extra regular battalions or converting 16 cavalry regiments it was decided to form 4 regular RTC battalions and convert the 16 Yeomanry regiments retained as divisional cavalry regiments and scout regiments IOTL to RTC divisional tank regiments. There was also money for 20 regular and 40 TA armoured car companies, which was used to convert 4 regular cavalry regiments and 16 Yeomanry regiments to armoured cars. The 16 Yeomanry regiments consisted of the 8 armoured car companies of OTL expanded into regiments of 3 squadrons and 8 regiments, which IOTL were converted into artillery regiments so that they could keep their horses.
The number of RTC armoured car companies could have been quintupled to 40 with the British Government paying the capital cost of the armoured cars and the Government of India paying the operating costs. However, what I am currently having happen is that 10 British Army in India and 30 Indian Army RTC companies were formed. Then in the late 1920s 4 British and 8 Indian horsed cavalry regiments were converted to armoured cars and the independent companies were disbanded so 36 former horsed cavalry squadrons replaced 40 armoured car companies.
More regular cavalry regiments would be converted to armoured cars in the late 1920s bringing the total on the British Establishment to 10 and the under strength RTC battalion in Egypt was still formed. Therefore by March 1934 ITTL there would have been 21 RTC tank battalions (5 regular and 16 TA) and 26 cavalry regiments with armoured cars (10 regular and 16 TA) or the equivalent of 46.67 regimental equivalents instead of 9.33 IOTL an exact quintupling of the real world. On the Indian Establishment were 12 cavalry regiments with armoured cars in 36 squadrons (12 British and 24 Indian) instead of 8 RTC armoured car companies, which is slightly less than a quintupling of OTL.
In terms of equipment it was going to be an exact quintupling of the numbers of AFVs and other tracked vehicles built and no qualitative improvements until about 1930. Therefore 5 A1 Independent Tank prototypes, 800 to 1,000 A2 Medium Tanks and 35 Birch Guns plus 5 times as many Dragon artillery tractors, armoured cars, tankettes (VCL and Morris-Martel) and miscellaneous prototypes. The turning point was going to be Specifications A6 and A7, with something at least as good and cheaper so that more than 30 A6 and 15 A7 would be built ITTL (instead of 6 and 3 IOTL) and the hundreds of A4 Light Tanks Mk I to III or IV built to 1934. I was thinking of not closing down Johnson's Tank Design Department because more money was available and/or Vickers having enough money through its quintupled tank orders to buy the services of Christie in the early 1920s.