Should couples have joint bank accounts or keep finances separate?

@GeniUs actually, it's Royricky using the robot, so there's still a human who wants to know.

@LordShadowfire Quick answer; when I got married we kept our accounts separate but my wife wanted us to have each other added to the others accounts. This had never been discussed before we were married and I was uncomfortable with it but without evidence to be so. We looked after our own bills as we had done before marriage but when my wife sold her house her outgoings dropped and since we lived in my house I was paying all the joint bills. One day she said to me I got £400 interest on my account last quarter, all the time I'm spending almost everything on bills. I agreed we should have joint accounts the bank screwed up the paperwork twice but it went through on the third time of asking (it was the bank and not her AFAIK). When I finally got access to her accounts she had a huge lump sum from the sale of her house which she was eating into every month as well as spending all her wages (Nurse, so a good amount to get through). I took the majority of the lump sum from her account and paid down the mortgage to about 20 grand and did this without discussion because I'm sensible and I didn't want the fight. She was still left with about 3 grand to fritter away.
There was a fight anyway and about 2 years later we were getting divorced.