So in this interview on The Krotons DVD, Frazer Hines tells how he once snuck into the studio during the lunch hour and got inside one of the Daleks just to roll around in it and play pretend.
Then he heard somebody come in and he froze so he wouldn’t get told off, and it was two actors who leaned on the Dalek he was in and started bad-mouthing the show. (Not knowing he was in there.)
Partway through their conversation, Frazer rolled away going “I HEARD THAT. I’M TELLING.” in a Dalek voice.