As you can see, the pin needs to be removed so I can get the links into the clasp ends. They look like push pins to me, but they also look as if they are fused to the link? Before I begin tapping away with a fine bit hard punch I thought I had better ask the more knowledgeable here.

 

I think it's a normal pin, but that the whole edge has been polished.

 

They're straight pins which are swaged into the links and aren't meant to be removable, unlike the other pins/screws in the removable links.
You could try a pin punch, but I fear that would break before the pin gave way unless you use a quality item.
There's only one way to find out.
Support the bottom of the link in a bracelet block, apply oil to both ends of the link and use a pin punch and a hammer.

 

Thanks guys, luckily I found an another set of BoR links in the bottom of my Felix bag of tricks that were better suited as it turned out. Turned out ok with a light polish.

Never thought about the swaging process - but yes, I can see that now. And as Dan says, polished up as well.