Please some possibly basic advice.

Our 1 series recently purchased drives exceptionally well, tight as a drum, quiet, smooth, but skates across the road as if it has shopping trolley wheels??

I had not driven it as I had it delivered, but upon using it today I can say its almost impossible to keep in a straight line!

The obvious,

It is fitted with brand new Michelin Premacy Alpin Winter Snow tyres, is this the issue? The wheels are tight, no play on track rods etc??

Help

Directional tyres fitted the wrong way around maybe? Or tyres over inflated? New tyres do take a little while to bed in but it shouldn't be as bad as you're saying.

Get a 4 wheel alignment done.
If the wheels are pointing in slightly the wrong directions then it will be twitchy.

They're all rotating the right way, but they are snow tyres, are they this bad on wet uk roads? Literally like there is an inch of turn on every wheel.

From what I've found after a few winters on snow tyres is that the handling does become more twitchy, but not so much as you describe Chrissy.

I just noticed the tyres looked a little soft, I took the car to the garage, the pump wouldn't even read the psi the rears were that low! Under 5 psi! They didn't even look that bad!!??

35psi later the car is entirely different, radically..

I had a quick look on line. Are your Alpins the runflat version? That could explain them looking ok at low pressure. I guess snow tyres are more likely to be designed to allow low pressure running for extra grip too.

Yes they are bloody runflats, and yes thats why they appeared to be ok,

Total school boy error, But I thought the car had BIG issues, Then all was rectified with a 50p coin in the garage!

Do you jot get tyre pressure warning sensors on it?? 5 psi - you may also want to check the tyre hasn't collapsed inside, I had a 30 profile on a 3 series that ate itself very quickly when driven under inflated.

Beemers seem to spec runflats for some reason... as do Mini's... possibly cos they are also BMW group.

Nah, it's just an ES and doesn't have the pressure sensor,

The tyres are brand new & I can see they are A -OK

If they are that flat, maybe they haven't sealed properly due to rim corrosion. Might need removing for rim clean and re-seal. Best keep an eye on 'em for a couple of days.

I had a 1 series for work years ago, after a trip to Kwik-fit the backend felt like it would wobble when changing lanes on the motorway.
Checked pressure on the tyre that had just been changed, think they forgot to inflate it.

50p !!

Only one garage around here charges 50p for air. All the others are 20p or Sainsburys is free

Glad the problem wasn't a major one though and sorted quickly

Must be Cardiff prices

Buy a cigarette lighter powered tyre pump for about a tenner and it will soon pay for itself.

Look out for cracked rims, I've suffered with my BMW

That's a useful thing to know about run flats.
I imagine that tyre fitters forget to inflate run flats more than people realise.

Hopefully, most people run away screaming from run-flats, so tyre-fitters won't be familiar with them...