I think they are Lucy's killers I think they are seriel killers they have gone on about how business is bad so what's best way to make business for a flower stall and undertakers is to make the customers yourself! They came from nowhere and this happens.
I also think tosh knows something or is part of it and that's why she's so angry the carters wouldn't report billy to the police plus I think billy knows something too

Frank Butcher Potato Peeler™

And also les said their son died years ago what if their son isn't dead and their son is "Charlie cotton"

They feel out of place and very Coronation Street at times (not a diss) but I can't help liking them. I hope they're not the killers but I would be intrigued to see how it would all play out if they were.

I dont think they are the killers but I wouldnt be surprised if Les dies within a year. It seems like they are bedding Pam in and making her interact with lots of people and Les lifts out. If Billy and Pam become friendlier then thats a mother figure for Billy and Grandmother for Lola/Janet etc Billy can take over the funeral biz.

I dont think they are killers either ^