15a plug

Hello - possibly a dumb question but my knowledge is a little basic!I'm looking at maybe having a practical household lamp on stage as part of a show, but I want to be able to dim it from my lighting desk. The one we have currently has a 13A plug and a dimmable bulb. If I buy a 15A round-plug...

Hi all,Bought some new 15A plugs from a supplier and they arrived today. I noticed something odd that I hadn't seen before. A slot in the top where you can see the earth terminal.Very loose speculation makes me think possibly for some kind of earth extension? Presumably these plugs are safe...