caught this sad news late on last night so i came here to say this.
one of my earliest memories is from about 69-70 when aged 4-5 ish i used a large woodscrew as the mole, getting the effect of it burrowing into the ground by getting at eye level with a table, then moving it up and down the opposite edge! a happy and precious memory influenced by Gerry Anderson.
R.I.P. Gerry, and my sincerest condolences to your family.