It's nothing new, this has been going on since privatisation.
Essentially, for every delay reason, there is a code, plus a responsible manager. Hopefully every minute is accounted for, certain every one is queried. With 24,000 trains running per day that's a big job.
It's not quite as simple as that, as you get TOC on TOC delay.
For example, a train gets stopped by a track circuit failure in Bristol, causing it 15 minutes worth of delay, and 28 other services. So the total minutes of delay is 420 minutes, possibly payable at £50-£100 per minute, lets say £80. So that's £33,600. Although the exact framework for compensation is more complex, and as you can imagine political at times and need an army of management to deal with.
Then those 28 services, affect other services, say by delay on single lines, stopping trains running slow ahead of fast trains, or trains taking up other platforms. So, lets say another 2000 minutes worth of delay is caused. Then those trains, delay other trains and so on.
This is why there is so many single track redoubling schemes going on.
You can quickly end up with delays with 10,000 -100,000 minutes of more and bills of millions, in fact some bridge bashes on busy main lines have ended up with third parties like hauliers with court actions for bills of £1 million or more.
The delays caused by the Hatfield rail disruption was the biggest number I know of, and I forget what the total was, but it was millions of minutes and led to the bankruptcy of Railtrack.
The skill of the railway operating staff is:
1: To identify and repair the fault, or solve the problem, within the framework of the rules and regulations.
2: To minimise direct delay
3: To minimise indirect delay.
Staff that do not minimise delay or cause delay are likely to end up out of a job or demoted.