Oil Leaking From Left Fork At 1200 Miles.

Try one of these



They are really expensive for what they are - a thin piece of plastic about as long as your hand. Cut one out of a plastic milk carton and it will do the same job.
Run it into the fork seal and round the stanchion. It'll pull out any small bit stuck in there making the seals weep. If it doesn't work then all it's cost you is an empty milk carton.
There'll be some instructions on Mr Google and Youtube I expect.
A weeping fork seal wont hurt anything other than you wiping it now and again. Wait until the next service and get the non leaky seals inserted (I assume you can get them for the new tinny Triumphs like the vintage ones).

 

There are Youtube videos showing how to do this.

 

The forks on these are quite low tech and easy to work on. Change the seals and fit some period looking gaiters at the same time, like those fitted to the Street Scrambler.

 

Hopefully there's no damage to the slider causing the leak. If so, then you might be able to carefully sand it down with fine emory cloth. If you're lucky it might just be dried bug guts or dirt that needs to be cleaned out.

The blue Motion Pro thing is less likely to break when you pull it out, but before they invented it I used to use a strip of 35mm film to do the same, but there's a little more risk of breaking a piece off.

Then if all goes well, install rubber bellows type fork boots or neoprene protectors so it doesn't happen again.

 

I'm often doing the above on our offroad bikes and it usually works, but not always obviously.
Weirdly the offroad bikes usually leak after a prolonged lay off then first time out, than when in regular use, it must be crud festering under the seal despite the bikes being put away clean.