Meerkats are one of the most famous animal families on the planet, animals that are now stars of screens both big and small. These furry celebrities are also part of the longest-running animal behaviour study ever, now in its 20th anniversary year. David Attenborough tells the full story of the study - from its pioneering days when it was a challenge to even get close to a meerkat, to the very latest revelations about these animals and their complex lives.