A quick update on this....DNO came out and after a quick wobble of main cutout and jiggle to tails they said they couldn't see a problem and to contact the service provider. The service provider are arranging to come and check the smart meter. £90 if no fault found.... watch this space.
I was called to look at a job for an elderly couple where the oven supposedly tripped the supply and then after a few minutes the supply came on again. An engineer was called to check the oven and it checked out ok. A few days later when the oven was on the power went off again. No power to...