Spending so much time investigating Ancestry's extended probate registers for England and Wales, posted on Wednesday, meant I overlooked a posting about UK, Poll Books and Electoral Registers, 1538-1893. At 4.6 million records it warrants your attention.
It's a miscellaneous collection from the London Metropolitan Archives, not just for London. I found records for Newcastle-upon-Tyne and Black Country ancestors.
Poll books list those who actually cast a vote, and the person(s) they voted for. Only
freeholders and those who owned property above a certain value were entitled to vote. You may find the voter's occupation given -- weaver, smith, etc.
I'm told this is another product of Ancestry's proprietary technology for computer indexing formatted documents, previously used to compile the US directory collection.