RCD keeps tripping....help!

[Fartnado]

The RCD switch tripped this evening. I unplugged everything and turned each switch back on. It seems the downstairs socket switch is the one that trips the RCD. So my freezer, tv, washing machine can not be used
Everything upstairs and the lights do not trip it so we so have hot water etc.
What do I do next???

Unplug everything on that circuit and plug them back one at a time to see if it is a particular appliance causing the problem? I'm not very good with electricity but I don't think that would be dangerous.

It is usually a watery appliance.

This includes kettles, washing machines, boilers, fountains, pool heaters, and outside sockets and lamps that rain has got into.

I realise I haven't unplugged the washing machine and dishwasher so will try again. Thank you!

We had this and it was the toaster.

It was the washing machine! Thanks everyone all sorted now hopefully!