Broad beans, should I plant out?

I've had some autumn sown broad beans overwintering in pots so far, with the view to planting them out sometime in March when the growing season starts. However, in the balmy south east, it seems we have been stuck in autumn for the last two months, and the broad beans have kept on growing to the point where the roots are now coming through the bottom of the pot. I wasn't anticipating this to happen, but then I wasn't anticipating such a complete lack of any cold weather up to this point, with much of the same predicted to continue into February. Given that they may be getting somewhat pot bound, would it be worth planting them out on the allotment now in their final growing positions, or should I leave it a bit longer?

I agree with BabbyAnn. It's so easy to be mis-led with clement weather like now, but it's only January so a lot can happen. I know they are hardy but I would pot them on as suggested.

They are outdoors in pots in the back garden at the moment, and have been since the cloche greenhouse got blown over the fence on to the neighbour's car back in December.

So they are completely exposed to the elements?

Yes, although the back garden is surrounded by 6ft fences but other than that, the broad beans at the moment have no direct protection from the weather.