This has dogged me for some time and when I got new tyres at the front the guy doing it thought the front left wheel was buckled and sure enough when I jacked the car at home that wheel would spin without any external force. I bought a tyre/wheel and alloy and the wobble though not as pronounced is still there

What could it be please?

 

Do you get a shake through steering from that wheel when braking by any chance.

 

No shake through steering when braking

 

Is the wheel slack on the hub. Can you do a test by holding tyre at 6 & 12 0'clock and check for slack. This bearing slack would be together with a rumble though.