Hi Louise,
encouraging results, but it seems clear one needs a lot of compost and manure to be succesful this way. I tried the no dig approach to growing potatoes this year with not much success using the Bill Brandt method, Bill is an American no-till regenerative farmer in the US. He spreads a layer of compost in which he places the potatoes and them covers them with a thick layer of straw. I probably didn’t spread enough compost or straw, looking at how much you spread. 8 inches or 20 centimetres is a lot, it would basically use up my entire store of compost/manure. Better get composting.