BBC TV show. Rocks, Twins, Aliens, Cabage smell, mountains

bullets

Only going by probably flawed memories but
Anyone remember a BBC show (probably Australian based)
from the late 80's or maybe 90's that featured a pair of Kids that were Twins ? (was a little like escape to witch mountain)

There was two ginger haired kids that were non-incidental twins.
Brother and sister. The Brother was a bit podgy and called Theo.
The girls name I cant remember.

It was out around the same time as Children of the Dog star and Chocky .

They basically explorer a house across some lake and there is a bad smell from it like rotten cabbage. Under the house we find out there are aliens
that look like Humans with sweaty/melty faces and their true form are like
slug like things that slide down white slide like things under the house.

enter some old grey haired dude that tries to train the kids up with "powers" and he gives them a stone each, one glows Blue the other grows red.

The end of the show after a few episodes show's theo having doubts about his powers and the girl being stronger. the white stones activate when together and form some red and blue rainbow like thing that wipes out the bad guys in the end.

~B

Mr. Denton

Didn't come to me right away but I went digging because I remembered it too and it was bugging me.

http://en.wikipedia.org/wiki/Under_the_Mountain

bullets

Ahhh your a star! thanks. Could not think of the name of it.
and its on youtube:
http://www.youtube.com/watch?v=zFbxNvABbq8

~B