What I am after is a female plug socket, the type that would match a male mains adaptor that can be plugged into battery or mains appliances. One that has a the two wires already attached as tail leads.
The one with the +ve and -ve on the same plug, concentric and then into a socket with a pin in the middle.
About 4mm diameter but lots of standard sizes available.
It’s for a hot wheel conversion to save shelling out pounds on D batteries.

I cannot think what they might be called or even get anywhere near on google.

Try searching for ‘DC Power Connector’ plugs and sockets – searching maplin maybe to find something to suit

If it’s a standard mod, maybe google for a guide as they may mention the part?

It might be standard, but we are thinking of overvolting the hot wheels booster to get extra oomphage.

DC Power connector…bingo. thanks Mac.

Top 4 items:

http://www.maplin.co.uk/c/cables-and-connectors/connectors/dc-power-connectors

It seems the socket on the equipment to be powered is actually considered Male. If you are searching for female you will find the plug.

https://en.wikipedia.org/wiki/Coaxial_power_connector#Male_.28receptacle.29

we are thinking of overvolting the hot wheels booster to get extra oomphage.

As a wise man once said, the light that burns twice as bright burns half as long. Try not to kill it in the process.

Yeah just a straightforward dc power connector. You’ll pick up 2.1mm male/female with screw holes for trailing leads pretty easily if you look under cctv equipment.

Didn’t every home have at least one of these in it back in the 80s?

Universal DC power supply, for Google purposes. Don’t forget to get the polarity right.

Looking at the images against female, it looks like a female I need, the part that would be in the device?

Cougar, mine has a selection of ends rather than the throwin star arrangement. So I need the other bit, it goes into, with two wires coming off.

EDIT…going to 5volts over the stock 3v supply, so not a massive upgrade and I’ll add cooling, maybe.

3 to 5v…whistles! May only be 2v increase, but its also something like a 60% increase.

Buy a fire extinguisher.

So I need the other bit,

Male rather than female, then.