Wilting generally indicates lack of water. Don't forget that until very recently, we had had a very dry spring. Also, I made the mistake in thinking that because it had rained a lot, my pots wouldn't need watering - wrong! The rain won't be able to get through to the pot very easily where it is, so I think you need to water it.
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Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.