Hi, welcome to GoY, sorry for the delay in you're getting any comment, I've just noticed your question in the unanswered questions section, I think the problem is lack of water, I understand Lincolnshire has been very dry so far this year, which may have been the cause of the problem, I know that you have had some rain recently, but try pushing a trowel into the soil, to see if the water has penetrated to the roots, and if not, give it plenty of water, in the ground you can't overwater it, Derek.