Several examples have already been provided but 2 points might be of further interest:
1. The Nottingham writer D.H.Lawrence uses the word in his novels of the 1920's
2. Reputed to have originated from the French word 'merde' meaning 'shit'. So, to be 'mardy' would mean to be behaving in a 'shitty' manner.
I grew up in 1950's Leicester where it was in common use.
The ending must sound like the French 'e acute' in order to render an authentic Leicester accent. It is particularly suitable used in conjunction with the word 'bleeder'.
A word used commonly in the Ilkeston - Heanor area of Derbyshire meaning the person is a 'cry-baby' or scared to attempt something.
*Childish, easily upset, cowardly - a word restricted to an area between Leicestershire in the South and South Lancashire/South Yorkshire in the North.
( 'Ey Up Mi Duck' The dialect of Derbyshire and the East Midlands - Richard Scullins & John Titford - Countryside Books. Published 2000 ISBN 1 85306 658 3
Childish, sulky. Easily upset and wants their own way all the time.
Mainly from the East Midlands although it does appear to have some use in the Manchester area.
A word popularly used in the Nottingham/East midlands area of england. Words with a similar meaning include: stroppy, moody, sulky, grumpy, childish etc.
Regional slang assumed to be derived from 'Moody' originating from Derby, and over recent years having gradually become more commonly used as far south as Northamptonshire and as far north as Manchester (in many episodes of Coronation Street for example).
It is used most widely to describe children when they are having a tantrum or an adult who is sulking when not getting their own way. It describes a person who is feeling sorry for themselves or is crying shallow, crocodile tears.
This fantastic adjective has risen to more widespread fame in recent times thanks to those lovely lads from Sheffield, the Arctic Monkeys who wrote a song called Mardy Bum about a girl who was really mardy. Now all those southern softies have latched onto this fantastic word, it won't be long before we are hearing Peggy Mitchell behind the bar of the Queen Vic calling Billy a 'Mard Arse'.
In Derby, where the word originates from, it is very common to hear people calling others 'Mard Arse'. 'Stop bein such a mard arse!' meaning 'Stop being so moody, childish, grumpy, etc'.
The word is also used commonly in playground banter. Rhymes such as 'Mardy Mardy Mustard, You Can't Eat Your Custard, Nah, Nah, Nah, Nah, Nah!' were commonplace in Derby schools during the 1980s.
What is so wonderful about this word is that it has a whole meaning of its own and even though assumed to be derived from 'moody' it is not quite the same.
It is therefore of interest to know that the Chinese have a word that has exactly the same meaning as 'Mardy', therefore, it should be accepted into the Oxford English dictionary as a recognised word.