Thanks chaps. Yes haven't had the fuel gauge (I think) but the Range went up to 750 miles at one stage, on less than ½ a tank... then back to normal a bit later.
I've read a whole pile of posts since posting, and I was cautiously coming to that conclusion, but best to hear it directly. I wonder if the pothole could have dislodged something... anyway, sounds like it's relatively safe to drive till the man with the T4 gets back from his honeymoon