As Sir David Attenborough covers the colonisation of continents by lizards in this programme, we look here at the three species that made it to the UK via the brief land bridges that remained with Europe after the last ice-age.

Of these lizards, two species -the Common Lizard and Slow Worm- went on to conquer many parts of the UK, while one species, the Sand Lizard, populated a number of the UK's sandy heathlands.

Get legless…

Most unusually named of all three species is the Slow Worm, a lizard species that has over generations become completely legless (at least externally it looks that way). In fact for years it was classed as a serpent until diagnosis of some particularly lizard-like features including the ability to blink (lizards, unlike snakes, have a moveable eyelid), differences in scale arrangement, and a forkless (albeit notched) tongue.

Surprisingly little is known about the Slow Worm compared to the other UK lizards – a result of its secretive lifestyle hiding amongst decaying leaf litter and loose soil as it hunts slugs. This immense appetite is what gives the Slow Worm its ‘gardener’s friend’ reputation, and this explains its presence on many allotments.

If your friend is an allotment-owner why not ask if you can put some ‘refugia’ down. Refugia are materials which attract reptiles due to their capacity to reflect heat, e.g. old carpet or squares of tin roofing. For more information contact your local Amphibian and Reptile Group (www.arguk.org) or contact our Wildlife Information Service.

Biting jaws…

One of the most dramatic scenes in Programme 3 is the free-for-all mating frenzy of the charismatic South African Flat Lizards.

Such spectacular mating frenzies don’t tend to occur in the UK species, but in the undergrowth of your garden mating is far from leisurely. In the Common Lizard and Slow Worm, males firmly seize females within their jaws, and if there is little struggle then mating eventually ensues. Although often it only takes a few minutes for the Common Lizard, Slow Worm females stay in the males’ grasp for up to 10 hours, and as a result you can often identify female Slow Worms from the scars behind their heads!

Episode 1: Cold Blooded in a Cold Climate
Episode 2: Battlefield Pond
Episode 3: Dragon's Den UK
Episode 4: Snakes in the City
Episode 5: Visitors to UK Shores
Epilogue: Froglife in Cold Blood

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BBC Life in Cold Blood
ARG UK
British Herpetological Society
Herpetological Conservation Trust