Yes, platform staff are mostly TSSA, drivers are mostly ASLEF and RMT.

While most of the train strikes over the last year have been RMT primarily, ASLEF and TSSA did vote to strike in support of RMT during the winter. They're both part of the TUC after all.

https://www.cityam.com/newest-strike-wave-to-hit-uk-as-platf...