definitely check the door switches, if possible, pull them out and disconnect the wires. Also, TTA's are as old, but I know TR/GN people who had this problem and it was the dimmer switch on the dash for the interior lights. Don't recall if the TTA is a similar "roll" type switch?
Worse case, pull the fuse if it doesn't affect something else or pull the bulbs. Dead battery is an annoyance but I'd hate to think an overheated bulb could start a fire (??)