British spelling is a method of spelling against all known laws of nature, much like belly button or fat fold sex.
The insertion of auxiliary letters is a common device in British lexicography, since the nation has yet to completely embrace Americanisation (which can effectively be compared to being bullied by your bigger, yet slightly less literate, brother). It is a relic of Britain's elitist and aristocratic past, a time when the more instances you could squeeze the letter u into a sentence, the more likely you were to become the next monarch. King James I attempted this, only to be told he was exempt as a); he was already the King and b); he was Scottish. As we all know, Scotland is quite distinct from Britain as a government entity, at least according to American belief (and even beef).
Alternative spellings, no matter how frivolous, are acceptable in almost all circumstances. Since the English language wasn't standardised until the early 21st Century -- when world leaders decided they ought to suck up to America -- people were, and still are to some extent, free to make up their own silly spellings for words and claim they are correct. William Shakespeare was known to do this in many of his plays, but it would prove his eventual downfall when a crazed American person hopped out of the Large Hadron Collider and shot him in the chest with an AK-47 he pinched from Cold War Russia. Apparently the attacker's brain capacity could not comprehend the sheer linguistic liberties Shakespeare took, which is kind of ironic considering his love of txting.
Non-use of the letter Zed. Whilst it's a common misconception that British dictionaries do not accept the American method of spelling words that end in '-ise' (standardise/standardize, exercise/exercize, choc ice/choc ize etc.), it is in fact much more flexible, accepting both '-ise' and '-ize' as well as '-izze', '-izzze' and '-isze!!!' (note the triple exclamation mark). In recent times, the Oxford English dictionary also introduced '-izzle' as an acceptable word ending, leading to much mirth on GCSE exam papers and Snoop Dogg to get an A on his English Language A-Level.