Theresa May had two spads on £140k back in 2018 and Alistair Campbell was on £125k nearly 20 years ago under Blair...so I think we can assume that Cummings was getting the going rate. As I understand it, the only reason this is in anyway newsworthy is that apparently when BoJo came to power, it was DC himself who decided to impose a "no Spad on more than £100k to show we are men of the people" policy.