I have a digital clock, which displays the time, for example, as shown in the picture aside. One day afternoon, I saw the time, not in the clock but in the mirror. I realised that the mirror image showed the time three and half hours ahead of the actual time. Then the actual time was ______.

In a mirror the four digits appear in reverse order and each digit is itself reflected, so only $$0, 1, 2, 5, 8$$ remain readable, with 2 and 5 interchanging. Trying the afternoon hours whose digits come from this set, the display 12.21 is reflected as 15.51, and 15.51 is exactly three and a half hours after 12.21. So the actual time was 12.21 in the afternoon.