Lot of those will be the Corbynites who left en masse.
Membership matters from the point of view of funds but the quality of members also matters. That applies to the tories too
The Conservative leadership poll at the end of 2022 to all members, a total of 140,000.
Labour despite losing members since 2019 still have three times the number of members, the Conservatives have.
Conservative membership is pathetically very low at the 14K mark (if the leadership contest is to be believe).
Why anyone would want to be a member of such a failed enterprise is beyond me.