'Ms Miller warned that UK progress on environmental policies more widely has been stifled by Brexit.' Can't say I agree with this sentiment. Brexit is not the thing making these decisions, the encumbent government is. Brexit might have facilitated them, but it's not the direct cause.
'This, compounded by a lack of action from Britain’s mainstream parties, means it is lagging behind its European counterparts, she said.' Exactly. It's time we start blaming the right target - in this case, the Tories.