enamelled wire for mains pt and opts

[numpty]

I don't know if there is anybody in this forum who knows about constructing transformers, but is it okay to use single coated enamel wire as opposed to double for mains transformers. I have used double coated in the past but i can't get hold of any now, but maplins do the single coated and i wondered if that would suffice. They claim it's for mains transformers but i have read elsewhere that it isn't recommended.