I'm taking a stand on this.
If you are still holding a ticket from a cancelled year, then you were obviously intending to go this year. Getting a refund now is because you have changed your mind and that should not entitle you to a refund. It's a loophole and might well push the festival over the edge.
I have removed posts suggesting that you do.
It should be added that if your circumstances have changed due to illness or similar AND you have a multi-trip holiday insurance policy covering the UK, then you should be covered by that rather than forcing the festival to indemnify your misfortune.