Didn’t someone on DIS a few weeks ago declare that adults don’t carry change or something? There was definitely some foolishness along these lines.
But in answer to your question, cash, and £1.77, although I have £1.30 in transit to the cafe with a co-worker, who will be buying me snacks with it. I leave it up to you to decide whether this counts as it could theoretically come back. Schroedinger’s cash, or something.*
*This makes it look like I thought up this mediocre gag, then back-filled story to shoe-horn it in, but I didn’t.