It really isn’t, when you take your core support for granted and then abuse them, it never ends well. Just look at Labour in Scotland.
Labour took a deliberate decision to move right in the 1990s and won a lot of national elections on the back of it. Then they had to pick a side in the most contentious and bitterly fought referendum in Scots history, with a sort-of centrist party ready to pull away indy-supporting voters.
The big difference is that if you’re a Tory-voting, Brexit-supporting, Mail-reading old biddy sitting on property in the south of England, there is no alternative party ready to grab your support. There is simply no way you are voting Labour, and equally unlikely you’d move to the LibDems given their stance on Brexit.