This anniversary special is quite interesting as it features excellent performances from all involved. The natural chemistry of Patrick Troughton and Nicholas Courtney for instance is one of the truly shining elements of this production. Also Richard Hurdnall does a remarkably good and under rated version of the 1st Doctor. It is most interesting to see the 1st Doctor paired up with Tegan as they both have intense egos which work brilliantly in tandem. Meanwhile we have the familiar couplings of the 3rd Doctor and Sarah Jane along with just strange choices - Turlough and Susan. This adventures captures the spirit of Doctor Who at it's finest, and is quite well written, acted, and executed for an anniversary special!