@SirSamuelVimes
They did NO ROAST POTATOES AT ALL. The day lives in infamy.
I thought my one potato per person was bad, but that is tragic.
Also, the same Christmas MIL did not do custard or brandy sauce with the pudding. It was cream or naked pudding. I hate cream. I don't think it was deliberate at all, just...odd. So last year I took every Christmas pudding accompaniment I could. I was allowed to have my brandy sauce but not allowed to have it on the table. There were a few other strange incidents that I shan't go into because they were so odd as to be identifying. DH phoned MIL on Boxing Day to check she was ok because of how she'd behaved & she denied it all.
At least we don't have to deal with that this year. 
the police ordered them to stop as they’d had a complaint from a member of the public who felt ‘worried and unsafe'
I've been "worried" & felt "unsafe" plenty of times in my life but only ever phoned the police once (for kids riding motorbikes on a footpath & almost knocking people over)