For any non-snooker players: the theoretical maximum break you can usually get is 147, by sinking all 15 red balls each followed by a black (the highest scoring coloured ball) for 15 x 1 + 15 x 7 = 120. Then sinking each of the coloured balls for 2 + 3 + 4 + 5 + 6 + 7 = 27. This makes the maximum break 147.

But Ronnie's opponent fouled at the start, which meant Ronnie was given the ability to nominate any coloured ball as though it were a red ball. He nominated the green as the free ball and sunk it as if it were a red (scoring 1 point), then potted the black (7 points). So he had an extra 8 points right at the start.

Then he managed to sink a red (1 point) followed by the black (7 points) a total of 13 times, and a red followed by the pink (6 points) twice.

8 + 145 = 153 (highest ever).