The Conservatives and, I think, Labour were opposed to the Euro, that is why we are not in it. On that subject Caroline Lucas is going with the majority.
British governments of all hues, come to that governments throughout the EU, who have supported it, have questioned almost every element in it at some time or another. The problem is on very few issues has they been in any accord about how it should be changed - and when majority voting was introduced to try and get action, The Brexiteers of all parties and none in the UK used it as an excuse to lobby for the referendum we had last year.
It strikes me that Caroline Lucas is boringly mainstream.