He was chemically castrated. What happened to him, especially with all he did for the war effort, was a travesty. Cracking enigma and everything else he did probably shortened the war by 2-4 years.
Then why not have a banknote dedicated solely to those that were castrated?
What happened to him was terrible - but no one actually knew what his war effort involved until decades later.
So his service to his country was never a mitigating circumstance.