Onion bolting madness

Twenty four hours without any beer. Yesterday I kind of struggled to get straight back from the allotment to my mum's, but I did.

With a couple of strawberries (loads of white ones on the allotment) and a bunch of onions I returned. From the onions I made soup out of what I could salvaged from the bolted few I'd dug up - using a pressure cooker to speed up the process and break down the fibres. 

What's left in the kitchen are the equivalent of large spring onions, but they aren't bolted!

I've been reading into why the onions on the allotment are 'bolting', which is when they send out a flower stalk and don't produce the layers of a conventional onion, and apparently onion 'sets' are more likely to do so over onion grown from seed as they are less tolerant of variations in weather.

Since winter sprung into spring the temperature has been very variable - the last week temperature at night has struggled to get over 8°C all week and day time temperature has been in the low teens too.

There are dozens of onions on the allotment which have bolted: perhaps I should have let them run to seed rather than cut off their heads as now they'll just die!

It seemed the only thing to do to stop them any further, until I read that once they've bolted there is nothing that can be done ...