2015-2016 Winter League – Table Tennis England has "strongly advised leagues to introduce plastic balls for the 2015-2016 season". The Derby & District Table Tennis League Executive Committee intends to support this advice. The Executive Committee hopes that the vast majority of matches will use the plastic ball during the 2015-2016 season. The ITTF list of approved table tennis balls, which contains some makes of celluloid balls, is only valid until 31st December 2015.
Plastic balls: Your questions answered. your questions answered.