Before the beginning of the 1917–18 season, the NHA was suspended and the owners formed the National Hockey League (NHL). The Quebec team did not field a team that year and he was loaned to the Toronto Blueshirts club, now run by the Toronto Arena Company. The club would go on to win the Stanley Cup in a series against Vancouver. After the season the Arena company formed the Toronto Arena Hockey Club and Mummery signed for the 1918–19 season. Unfortunately, the season was a disaster as the club had poor results, weak attendance and it folded, prematurely ending the season.