For those who can't solder / don't want to and are concerned about the mechanical connection on the crimps, take a look at the big (4mm) cable connectors you can buy in strips from the DIY places*. They are rated at 13 Amps, have a solid conductor right through them and offer a secure screwed connection to the wire and the kettle element.
You still have to insulate as you've got the risk of liquid ingress and the securing screws are, with difficulty, touchable. I used them for half a dozen brews until I got hold of a cheap soldering iron and fitted the Maplin 10 Amp hot sockets for convenience, I also used solid core cable from the plug to the connector as it's just 'better' in my view for this connection type. I like to remove the elements every couple of brews and clean them to make sure there aren't any hot spots due to the the sticky wort building up, as shown in BY's photos, hot plugs make this a simpler process.
*if you don't know what I'm typing about here, best stick to some other method as getting it wrong has potentially unpleasant consequences.