column to dash mount bolts loose?

The track rod ends were my first thought, too. But I checked mine and there's no play in them at all, whereas the kingpins are flopping around like a twig in a wellington boot.

where does that fit?

tim - don't think so, it comes through the wheels and shakes the car

Kingpins, I tell you. It's the only thing I can find wrong with my car and it has exactly the same symptoms as yours. I'd even spell the noise the same ...

Sorry. On the steering rack

Those resonating vibrations in the steering are invariably the result of too much play 'somewhere' in the steering, especially if they occur at relatively low speeds ( 40 to 50 mph?) on shallow bends.
Kingpins, track rod ends, sliding bush in the rack and wheel bearings should all be checked, with the culprit most commonly being the kingpins or track rod ends.

Note that if this fault develops suddenly, the security of the bolts holding the steering arm to the hub carrier should be checked asap.
It's also not unknown for the welding of 'turned' arms to let go...

Checking for play in the kingpins is straightforward, however when checking track rod ends, set the steering straight ahead and the steering lock on, if it's fitted.
Push the rear edge of each front wheel inwards hard, to see how much 'give' there is against the inboard spring in the track rod end housing.
As the track rod end balls wear, the play can be taken up by that spring, so pushing the wheel gently may not reveal all of the free play.

Using the same method, watch the inner ends of the track rods to see if they move in and out of the front axle when the road wheel is pushed and pulled in the horizontal plane.
There should be no more than a trace of movement there, otherwise the sliding bush on the rack may need to be replaced.
Luckily, they're not that difficult to fit, but the best approach is to rebuild a spare rack.

ken

That's probably the first thing to check actually.

It's kingpins checked all axle and steering components, found o/s KP has lots of play and n/s has a little, also found slight play in n/s wheel bearing everything else is good.

russell you should have more faith in your work, those arms look like they were made in the factory

Told you.

yeah ya did