Bertram Collacott
From Tardis Wiki, the free Doctor Who reference
Bertram A Collacott operated the Silurian pet, or "Bertram the Friendly Monster", and served as an uncredited visual effects assistant on Doctor Who and the Silurians.
The dinosaur was listed on script cast lists as "Bertram, the Friendly Monster", after Collacott, and played by "himself". (REF: Who-ology)