That's good news (I think). To be fair to my local mechanic, I spoke briefly to him about Intek 20hp motors and potential governor failure without talking specific model and type numbers, so he wasn't to know my engine wasn't fitted with an ACR. I didn't realise there would be models with and models without a feature like this.
It's now raining at our place after days of high heat and humidity, so until I fix the ride on, it's back to mowing a couple of acres by hand. At least it keeps me fit.
If I attempt an adjustment of the governor (as per suggestions above) and then start the motor, do I risk damaging it if in fact the governor has had a failure (internally)? Should I drain the oil to look for evidence of failure before doing anything else? I assume there would be some pieces visible in the oil if it's broken?
I would be happy to take the mower to the local repair shop, however they have no room for any more ride ons, so to get it looked at in the near future, I'll probably need to remove the engine and take to them. Hence I'll keep at it myself for the moment.
Thanks for assistance to-date AVB. I will keep everyone informed as to the outcome of my investigations........