70mph in top gear???

[Jules-C]

I have a Speedo that occasionally goes weird, apparently I was doing 125mph around a roundabout I usually take at least than 30 a couple of weeks ago

Check the route of the speedo sensor wire in particular by the brake disc.  Weird speedo readings are often caused by the edge of the disc wearing through the insulation and contacting the copper wire and sending confusing pulses to the speedo