A fork of Rural Dictionary
Not used at all in day-to-day English in London.
Harry Potter and the Order of the Phoenix is perhaps the only example of "wotcher" being used.
An English colloquial greeting that perplexed thousands of Americans upon reading Harry Potter and the Order of the Phoenix. Tonks uses it as a greeting, obviously requesting a sexual favor that will take place in the 6th book.
"Wotcher, Harry!"
("I want to feel you inside me, Harry!")