Hi, I've recently bought a Victorian house and I've been having a look at doing a few bits of DIY. I unscrewed a light switch today, to find that the Live wires are all connected together, and (I think) that the earth being used as a Neutral (all the yellow/green wires are connected together). Please see attached image.
How bad is this? Is this 'not up to modern standards but you'll be ok' or is this 'call an electrician ASAP'?