Who was the first person in snooker history to achieve the highest possible break of 155?

Cope has the distinction of being the first player in snooker history to post a verified 155 break achieved in a practice frame in 2005.

Jamie Cope (born 12 September 1985) is a former English professional snooker player. He has reached the finals of two ranking tournaments and the semi-finals of the 2011 Masters. Cope entered the top 16 in the world rankings earlier in that season, but thereafter developed a tremor which has been attributed to being either an essential tremor or the yips, which makes his cue arm shake. This condition has caused Cope to slip markedly down the rankings in recent years and caused his relegation from the main tour at the end of the 2016/2017 season.

Cope had an impressive record as a junior, but dropped off the Main Tour after two largely unsuccessful seasons. However, he finished top in the Challenge Tour for emerging players in the 2004/05 season, winning two of its four tournaments. This enabled him to return to the Main Tour. His stated intention in pre-season was to finish the year in the Top 48, a tough target which he technically achieved by default after Paul Hunter's illness. He reached the last 16 of the season-opening Grand Prix tournament. Later in the 2005/2006 season he reached the same stage of the Welsh Open and China Open. Those three last-16 defeats were all 5–4. During the season he claimed wins over Joe Perry, Steve Davis, John Parrott and Alan McManus.