The Drop & The List, by Mick Herron

These are two more Slough House-adjacent novellas that fill in the gaps between some of the full novels. Actual slow horses make only token appearances. The stories feature ‘milkman’ John Bachelor, who is charged with monitoring superannuated spooks and whose future looks increasingly bleak as he desperately claws to hold his place within the security services. Two future slow horses are introduced and, if you read this out of order – which is likely as the novellas are not well promoted – your heart will ache for what is to come for them.