Thanks Redser. Bigger pots for tomatos worked a treat

I start toms off individually in 2 inch pots in the propagator, then onto the south facing window in trays until I am ready to put them out into the pollytunnel under a frost fleece. I leave them in those pots until I feel it is time to put them out into the pollytunnel floor in large 20L pots with a handful of chicken manure. The roots would usually be well coming out the bottom of the 2 inch pots so I am very careful when potting on to the 20L pots. I have a tray under the pots to manage the water. I let them get to 5 trusses and then pinch out one leaf above that.