FWIW, I asked Google a very simplistic question
"how much would it cost to put police on every passenger train in the uk?"
And this is what their AI Overview came back with : -
AI Overview
The estimated annual cost to put one police officer on every passenger train simultaneously operating across the UK would be approximately
£7.7 billion, with initial setup and recruitment costs likely adding several billion pounds more.
Breakdown of Costs
The massive cost stems from the vast number of officers and significant associated expenses required for a continuous, nationwide deployment.
Number of Trains: Around 18,000 passenger trains run daily across the UK rail network. While not all run at the exact same moment, peak times see a substantial number of simultaneous services. Assuming an average of approximately 5,000 to 7,500 trains are in operation at any given moment across the 24-hour cycle (accounting for peaks, off-peaks, and night closures for maintenance), an equal number of police officers would be needed for a single shift. To provide 24/7 coverage, this would require at least 4 shifts worth of officers to cover different times and rest days. This means a standing force of approximately 20,000 to 30,000 new British Transport Police (BTP) officers would be needed in total.
Cost per Officer: The full economic cost of employing a police officer (including salary, pension contributions, National Insurance, equipment, support staff, and overheads) is substantial. The City of London Police reported an average full economic cost of £105,752 per officer per year in 2023/24. Other estimates for basic salary and associated costs range from £50,000 to over £60,000 annually per officer.
Total Annual Operating Cost: Based on the estimated number of officers required (20,000 to 30,000) and an average all-inclusive annual cost of approximately £100,000 per officer, the annual operating cost would range from £2 billion to £3 billion just for salaries and direct overheads. When factoring in the entire 24/7 operational requirement and logistics, the real annual cost is likely much higher, reaching the multiple billions figure.
Initial Costs: This figure does not include the significant one-off costs of recruitment, vetting, and initial training for tens of thousands of new officers, which can add substantial further expense (one estimate puts the cost to train a single officer via a specific program at around £210,000 over three years).
For comparison, the entire annual budget for the British Transport Police force in 2021/22 was approximately £328.1 million, for a force of around 3,113 officers. The proposed initiative would represent a massive expansion of this budget and force size.