The Doctor in shirt sleeves and waistcoat in the TARDIS.

The four part story, Meglos, broadcast in September and October of 1980, saw Tom Baker play a very strange doppelganger, Meglos, a cactus like creature who had the ability to shape shift for a limited time. The scenes where the cactus spines reverted through The Doctor's skin took many long hours in make up, although sharp eyed viewers couldn't miss the fact that the cactus gloves ended at Tom's wrists.

Meglos's True Self Breaks Through

The Doctor and Meglos Face Off.