I would get this changed as soon as possible. You stand a chance of the bearing failing completely and seizing. This could cause the wheel to be dislodged and cause a serious crash.

A vanishingly small chance. Has anyone ever had direct experience of this during this century? Even if a roller or two of the bearing disintegrates, the inner race will still rotate inside the outer race, albeit extremely noisily. As anyone who has changed a noisy bearing will know, it can be almost impossible to detect with the naked eye the causative surface problem of any of the rollers.

I had a front wheel bearing fail without warning, the wheel and drum moved far enough for the pistons to pop out of the wheel cylinders so no brakes. Fortunately I was approaching a roundabout late at night so no dramas, stopped using handbrake and got it towed home to fix it.

You stand a chance of the bearing failing completely and seizing. This could cause the wheel to be dislodged and cause a serious crash.

A vanishingly small chance. Has anyone ever had direct experience of this during this century?

I had a front wheel bearing fail without warning, the wheel and drum moved far enough for the pistons to pop out of the wheel cylinders so no brakes.

Drums on front wheels? I assume that was on a car dating from the middle of the last century (Ford 105E?) and which probably had not been examined annually as thoroughly as today's MoT.

John F, you correctly guessed make and model, 1960s MOTs were, like today's, somewhat variable in items where the tester had some scope for using his judgment.

There are still classic cars on the road which it was thought should be exempt from official MOTs, trusting owners to certify them as fully roadworthy.

I had that exact problem with my old Focus when it was about three years old. I was convinced it was a wheel bearing, having had wheel bearings go on other cars I knew the sound. Local garage I use said nothing wrong with the bearing and was probably the tyre, something to do with the tread blocks wearing in a strange pattern. When I came to change the tyre later in the year the noise went.

If it does turn out to be a bearing I would suggest getting both sides done. In my experience when one goes the other won't be far behind, they will have travelled more or less the same distance.