The speedometer may indeed read
over by that margin (and indeed those in both the Smart and the Jetta do just that), but had I challenged the fine, I'd have risked losing my licence for the more serious of having a vehicle that, by virtue of the
under-reading speedometer, was technically unroadworthy. My defence would have been that the Dolomite's speedo is known for becoming inaccurate as it ages but they'd simply have said that I should have done something about it. Like fitting the new one that's been in the kitchen for ages.

Would that the constabulary applied the same "zero tolerance" approach to proper criminals.
But as I started out with a restricted licence and had, a few years earlier - during a change of address, lost my B1 entitlement because of a DVLO cockup, the course fee was far less to fork out than the solicitor wanted to take on the licensing agency. And even then, I'd still not have gained a licence dated to expire only once I'd reached 70. It's an ill wind, etc.
Willy Eckerslyke wrote:.... Why was there a marker when you accepted the alternative to points?
Errindoors took that option when caught doing 33 in a 30 zone, and didn't need to send in her licence.
It's optional in cases where there are existing, but time-expired points on a licence. I had three on there from ages ago and didn't mind sending the licence off in the belief that those points would be removed, as indeed they were but on a 3-year licence, the course was supposed to be noted for information.
Your significant other's experience also demonstrates that the 10% thing only applies where it suits the powers that be in certain areas, or where a prosecution is made under the construction and use regs, a route that can be seriously costly for the poor motorist.