Not as bad as 10,000%, but the bank of england estimates an average inflation rate of 4.2%[1], so it's within an order of magnitude. (25M - 300) / 300 is only like 8200%, but bank of england puts the current value of 300 1917 pounds at 21283.44 2020 pounds, which is "only" 6994% ([21283.44 - 300] / 300).
[1]: https://www.bankofengland.co.uk/monetary-policy/inflation/in... 300 pounds, 1917, and 2020.