What climbing vines/flowers to use on pillars at front of house????

Depends where you are to some extent. Do you want a flowering vine or just foliage? There are tons of them. Ivy doesn't flower and does well in most climates. YOU could also use Morning Glory or even Peas that would give you flowers and produce

You don't indicate in what climate you live so I will assume four seasons. When vines drop their leaves in winter they look very ugly twined around metal pillars. Why can't you remove a flagstone and plant directly into the ground, that way you can plant an evergreen that will hide the steel pillars all year. I would suggest one of the columnar junipers, they're dense and can be sheared. They're also available in several colorations, I happen to like the blue grey varietals. Of course there are other solutions such as painting the metal a color that blends in better, or covering the pillars with lumber to match your house... there are also vinyl columns that can replace or slip around the metal pillars and in many configurations.

OK thanks for the advice guys. I fancy the idea of vines and might pull up the flagstones, would a large flower pot not suffice then? Has anyone tried jasmine or passion flower? These are 2 varieties that appear may fit the bill quite well....

I'm based in Manchester, UK so we have cold winters (doesn't go below -5 degrees C) and summers are mixed....

Using flower pots around the pillars sounds like a good idea.