[jsgreen89]

Runners and French beans are one of the few plants I never try to sow too early, mainly because there is always plenty of time to get a crop before the Summer ends. Next week sowing for me.
Salmo's advice to nip the growing points is interesting and could be the ideal solution. Regardless of frost, runners get blown about at the best of times when first planted out, let alone being rather too tall for the time of year. I wouldn't plant out yet. If it were me, I would hang on, cut the growing tip somewhat, and sow an interesting different variety as some back up. Might get two crops, as long as you have enough bamboo to spare.

Excuse my ignorance, but when can you pinch the tips? I planted 3-4 beans in pots indoors just for the heck of it, and one (Cobra French bean) is now 15cm tall after only poking through the soil 3-4 days ago. There is only one pair of leaves right at the top that haven't even fully unfolded. Shall I leave it for a while longer?

They sound like they haven't had enought light, but not to worry - you could always use some foil behind them to help when the other stems show. I'm not sure how many leaves a stem needs to have before you pinch out the top, but I guess about three pairs?

Hmmm they've been on a south facing windowsill so should be ok. Should I just plant them out??

[Yorkie]

Only if you can guarantee being able to protect them from frost where you plant them out.  It is still only April.

[Muppetgirly]

My runners look like triffids already  

They are hardening off now, so will go in a couple of weeks early, but hopefully will be ok.

[Paul Plots]

My runner beans (for once) look just right to me. A good dark green, well leafed and no more than 10 cm high. They've been outside for more than a week but not planted in the ground yet just in case we have a very late frost.

I started them off inside the aviary (where the birds couldn't get them) as the minimum temperature in there was about 5 or 6^oC. From there they went into a cold-frame with the odd over-night in a cool conservatory when frost threatened.

I'd take a chance and put leggy ones out and leave them to get on with it... and sow some more too. Saved seed costs nothing but the time it takes to collect it and compost is a cheap as dirt.