‘You know why they call this Slough House?’ Lamb went on.
‘Yes.’
‘Because it might as well be in—’
‘In Slough. Yes. And I know what they call us, too.’
‘They call us slow horses,’ Lamb said, exactly as if River had kept his mouth shut. ‘Slough House. Slow horse. Clever?’
— Slow Horses (Mick Herron)