So I've had a search here and can't find the answer.
Went out this morning and no speedo and ABS light stayed lit.
Home and have cleaned both speed sensors and tone wheels.
Then regarding front sensor
1/ disconnected
abs light on constant
2/ reconnected
light flashing
3/ rotate wheel
Speedo now works, got it up over 5mph
Light flashes
4/ disable abs
Light on constant
Speedo works
Heading to the rear one now.
I presume , ha, if the Speedo works the sensor is working.
Cheers