This is Half Pint, a very beautiful SINALOAN MILK SNAKE.  This species is usually found in Mexico in the wild but Half Pint was born in Tetbury in Gloucestershire! 

Milk snakes get their name from an old myth that they used to go into barns to suck milk directly from the udders of cows!  People believed this to be true because milk snakes are often very common around barns which house cows.  The real reason they are attracted to barns is because barns are also home to rodents, such as mice and rats, which are what milk snakes like Half Pint like to eat!

A milk snake's very distinctive pattern of red, black and yellow/cream bands, closely resembles the pattern of some of the venomous coral snakes found in the same geographic areas.  This mimicry almost certainly offers the milk snakes protection from predators, which will see the colours as a sign of danger. 

In the case of the north American milk and coral snakes there is a really easy way to tell if the snake is a venomous coral snake or a harmless milk snake.  The pattern of a coral snake always has the red and yellow bands touching (not the red and black) whereas a milk snake never has the red and yellow bands touching, only the red and black as demonstrated here by Half Pint! 

I have owned Half Pint since the end of July 2006 when he was only a few days old.  At that time he was tiny as you can see below, only measuring about 20cm in length (hence the name Half Pint as he was a very small milk snake), whereas he is now fully grown at about 1.5metres!