Something is pushing up from below, something of a smaller diameter to the rubber mount. I知 trying to work out from the exploded diagram what configuration would cause it to look like that.....but I知 struggling.
The shoulder on the top of the strut is about 2mm wider than the threaded part that goes up through the top mount :
This shoulder sits on the lower strut washer inside the top mount
You can see the silvery ring where the top of the strut has been pressed against the washer. On the LC, the washer punches through there. I believe Ian M (of ABS fame) also said he'd seen a few Carlton GSi's do the same thing. Once punched through all the strut load is transferred to the metal tube up the middle of the top mount, rather than being progressively distributed into the rubber by the washer. To me, that looks like what's happened here (assuming the washer was actually fitted in the first5 place)