Speedo failure is an MOT failure, surely?
Not really unless the tester has reason to drive the vehicle to do say a Tapley test,normal going on a car isn't driven when on test
It's on the rolling road for the brake test and is definitely a fail.
Speedometer
The car will fail if a speedometer is not fitted, is incomplete, inoperative, has a dial glass broken/missing or cannot be illuminated.
Copied from current MOT Inspection Manual
6.7 Speedometer
InformationThis inspection applies to all vehicles first used on or after 01 October 1937.
If the dial glass is cracked, it is not a Reason for Rejection, providing:
there is no possibility of misreading the speedometer or
there is no possibility fouling of the indicator needle or
the cracked glass does not create a safety hazard.
A Tachograph is an acceptable alternative to a speedometer providing it satisfies the requirements of this inspection.
Method of Inspection1. Check that a speedometer is fitted.
2. Check the condition of the speedometer.
3. Check that the speedometer can be illuminated.
Reason for Rejection1. Speedometer not fitted.
2. Speedometer incomplete, clearly inoperative or the dial glass broken or missing.
3. The speedometer cannot be illuminated.
In practical terms provided physically the speedo is undamaged, its function is not checked. My local MOT guy would not fail a car for a non working speedo, may give an advisory. If a working tacho fitted, that is an alternative to a speedo anyway under latest regs.
HTH