An emergency staking job was called for.
The first thing that I noticed when I removed their mesh covering was that the plants had nearly reached the top of their structure:
The two middle PSB plants were affected. The end ones were still upright.
So as well as staking the plants, I needed to raise the height of the poles. Fortunately I have a fairly comprehensive set of aluminum rods these days, so I was able to augment the existing 1-metre rods by a further 40cm using extension rods. I think the height will now be sufficient to allow the PSB to keep growing until it no longer needs covering - i.e. in the Autumn.
I hammered-in a 4-ft hardwood stake for each plant, and then loosely tied them with a couple of turns of soft string.
I was surprised how bent the plants were, considering that they had only been on their sides for about 12 hours. Hopefully they will soon straighten up again.
In this next photo you can see quite clearly the rows of Radishes that are growing alongside the PSB. To be honest they have not done well (due to lack of light) and only about one plant in six has produced anything useful. Most of them have plenty of leaf and long lanky stalk, but little useable swollen root. In the recent cool wet weather the slugs have had a Field Day with them too.
Anyway, the mesh covering went back on as soon as possible. This is protecting the PSB from butterflies and insects such as Whitefly.
With the additional height of the frame, the mesh only just reaches the ground now.
So there we are, crisis averted! The PSB would have needed staking soon anyway, but the heavy rain last night simply forced me to do it immediately.