The Mu Meter, produced by ML Aviation at White Waltham. I was sent to go and be introduced to this machine. It proved to be very accurate, even showing the different braking action on either side of the runway and the touchdown area compared with the rest of the runway. The amount of paper scrolls it produced was a problem though, try putting that lot in a file!
ML towed the demo model behind a Jaguar XKn "It's accurate up to 120mph" said the man, "No ****ing chance!" said the MTO at our unit in response to a particularly obsequious request to swap 'Rover'.