In reply to Martin1978: I ended up buying the Berghaus jacket today, same as the montane featherlite (super light and packable, windproof, breathable and dwr) but half the price at the outlet store (I paid £26 for it!)
I figured that at the price and pack size if it wasn't right for running it would be ok for other stuff short/fast evening biking/hillwalking etc. Might even make a decent belay jacket oer a microfleece for a lightweight set-up.
Anyway, went running in it this afternoon and it's ok! Arms were a bit damp from sweat but otherwise it breathes very well and kept the damp/chill off.
I will get a gilet when I see one on sale somewhere, but this will do for a multitude of sports and really bad running weather.
Cheers for the help all.