Speedo calibration - sort of

[TVRmuppet]

My car is of 1994 vintage and the speedo was reading way out. About 15% at 100 (Rolling road). After some deliberation i decided to bend one of the "fingers" away from the speed sensor so that it would not be detected. I tried the car with a sat nav and the accuracy had improved. Bent another finger back diametrically opposite to the first and tried it again.
At 69 on the sat nav it reads 70 and at 88 in reads 90. Thats near enough.
Thought this might be of use to others. Simple fix.