Meaning, origin, and usage of “cor lummy”

I came across an expression I’ve never seen before when reading a Kate Atkinson novel. A quick internet search netted little information apart from a possible cockney origin as a distorted form of “god, love me”. Does anyone have any more information on meaning, origin, and usage?

Update

Here is the excerpt from the novel:

‘You’ve been in a fight!’ Amelia looked at him for the first time but when he caught her eye she looked away. ‘How exciting,’ Julia said. ‘It was nothing,’ Jackson said. (Just someone’s trying to kill me.) ‘What day is it today?’ ‘Tuesday,’ Julia said promptly. Amelia grunted something that sounded like ‘Wednesday.’ ‘Really?’ Julia said to her. ‘Cor lummy, how the days fly, don’t they?’ (Cor lummy? Who said things like that? Apart from Julia?) ‘I always think,’ Julia said, ‘that Wednesdays are violet.’ Julia seemed in an exceptionally merry mood. ‘And Tuesdays are yellow, of course.’

Solution 1:

It is indeed a euphemistic or 'minced oath' version of "God love me" - with the verb, here, in the optative mood ("may God love me" or "as I hope God loves me") to invoke the Deity as guarantor of the speaker's sincerity. An analogue is "corblimey" < "God blame me", that is, May God impute sin to me (if I'm not speaking the truth).

• ADDED, 3/14/17: An anonymous reviewer suggests that blimey derives from blind me. That seems equally likely, and appears to be the sense in which the word was understood by late 19th-century observers.

It's 'cockney' in the broad sense of 'colloquial lower-class British', but it's not restricted to the area within earshot of Bow Bells and it's not rhyming slang.

Solution 2:

Partridge (2008) says:

cor lummie!; cor lumme!; cor lummy! used as a general-purpose expletive. A cockney variation of 'God love me!'; almost stereotypically Cockney but later use tends towards irony. UK, 1961

Although it's probably from around the late-1920s to mid-1930s; Cor lumme! appears in a number of magazine snippets in Google Books.

According to the OED, Cor is a vulgar corruption of God and first documented in J.B. Priestley's Angel Pavement (1931):

Cor! — you're in the wrong part of the theatre, boy.

Lummy is also a corruption of (Lord) love me, first quoted in J.D. Brayshaw's Slum Silhouettes (1898)

Wot! Pay for me death? Oh, lummy! not me.

The OED also quotes D.L. Sayers' Gaudy Night (1935):

‘Lor' lumme!’ I says, ‘there's old Winderpane gawn.’

Lummy is also slang for first-rate, and first documented in Dickens' Oliver Twist (1838):

Jack Dawkins — lummy Jack — the Dodger — the Artful Dodger.