Tyre wear issue.

A strange one but my front nearside tyre wears on the outer edge, the spare must've been on there at sometime as it a replica wear pattern.  The off side wears as it should , the tracking has been checked and is fine .. it's just passed it's MOT  so nothing obvious.
 I checked the brake cailpers and they slide as they should ...it does pull to the left all the time ...not arm wrenching and all of us that drive it have grown to compensate over the 3 years we've owned it..  
  The swivel does weep a bit  but just a smear ever so often .  The kingpins were sorted a couple of years ago  and that is probably 8000 miles , so shouldn't be an issue ..
 To be fair It's more for my "why didn't I think of that " that I ask ..no one else is bothered 

First thought is it's the roundabout tyre ie the one that takes most wear under normal conditions. Second thought it could potentially be worn or misaligned suspension bushes and or mounting points?

My father in law had a Nissan Xtrail that wore out tires a bit fast and only on the (left?) outside. As it was under warranty when bought, he took it to the shop to complain. The seller came up with an amazing theory that the tyres wear out on the outside on one side first from the earths rotation and that on the southern hemisphere it is the other way around. And then said something about it being more obvoius on servo assisted steering.
My Father in-law allmost believed the explanation

First check the tyre pressure, then alignment and of course worn bushes like Lambert says.
As a rough guide you could use a tape measure to check the toe-in. Should be a couple of degrees so a few mm narrower between the front of the front wheels than the back of the front wheels. But not like more than 5mm, then I would take it to alignement

I got a strange one on my Swift where the softer winter tyres wear evenly and the summer tyres wear out faster and unevenly. It is the same offset wheels and sizes. I know it is not so well aligned, I bought it with a dented front sub frame traverse where the lower arm sits. Straightened with a sledgehammer and aligned with eye-sight and a tape measure.
(Not at all recommended!)
But it drives fine and straight-ish.

I'd suspect a bent axle tube if the kingpins and balljoints are fine.
Get the camber angles checked.

The tyres should wear flat across- one of the advantages of a beam axle over poorly implemented "indeependant suspenshun".

Steering pull and uneven tyre wear point to something bent or worn. Incorrect tyre pressures won't help either, though one assumes that was the first thing you checked.

The MOT is to check for problems big enough to affect safety; that is not what you have here. You want to get it examined in detail by a 4x4 suspension expert to find the problem.

Or ignore it, since there is not much point in trying to fix every little thing on an old Jimny.

I find this an interesting discussion - here's why...

Back in January when I took my JC74 in for it's first service, there was a young lady with a JB74, that, based on the registration, couldn't have been on the road for more than eighteen months or so - she'd brought it in because the near side front tyre was almost completely bald & the other three were fine.

The dealer techs took the car into the shop and they brought both vehicles out at the same time so I was able to "eavesdrop" - their diagnosis was the steering stabilizer which they did not have in stock, but would order & replace under warranty.

My diagnosis matches facades' - it's most likely a bent axle tube.