Sounds like a drought problem, doesn't it. Gently remove the plants and inspect the rootballs to see whether they're dry or not. If your pots have good drainage holes which aren't blocked, and they're not standing in trays to catch the water, water freely till it runs out of the bottom and away.

Thanks bamboo, just checked and roots seemed moist not dry......are they likely to come good again if i continue to water or should I look to replace them.....stalks are still green but leaves look done for !

Stress can easily cause plants to drop their leaves. If you have ben having the heat a lot of England has you need to be doing major watering.

Keep watering, give a bit of shade from hot sun in the middle of the day - no British plant, but especially a young one, will be happy with this level of heat at this time of year - 25 deg C indeed, ridiculous, specially when I can remember years when its snowed in April.