What speedo?

I got to work today wondering what the hell my speed was, guessed the speedo cable had snapped. So had to work out my speed using rev counter and following other road users, 5th gear 5,000 rpm should be about 70mph. As for the 50mph speed cameras on the M3 road works, I just hope the person I'm following is not speeding. Can't afford another 3 points, else I'll have a ban. When I had a look at it lunch time it turns out said cable had broken, so I'll have to order a new one. £10 oh well at least it wasn't the speedo drive unit.