In Meet the Huggetts, a BBC 7 radio show from 1959, Mr. Huggett (Jack Warner) kept saying,
'Lummy',
which, of course, is, as you would expect and interjection of surprise.
My Penguin Dictionary describes 'lummy' or 'lumme' as 'slang', but the Concise OED says it's 'vulgar' and derived from 'Lord love me'!

My mum was always saying,
'Lummy duck',
which, if that's Cockney rhyming slang, could be blasphemous - YIKES!

Nick from England
In Meet the Huggetts, a BBC 7 radio show from 1959, Mr. Huggett (Jack Warner) kept saying, 'Lummy', which, of ... Dictionary describes 'lummy' or 'lumme' as 'slang', but the Concise OED says it's 'vulgar' and derived from 'Lord love me'!

The online OED gives that derivation and some quotes but does not classify it as slang, vulgar or anything else.
My mum was always saying, 'Lummy duck',

That might be a shortened version of "Lord love a duck": http://www.worldwidewords.org/qa/qa-lor1.htm
Michael Quinion discusses possible origins and concludes:

Perhaps the whole point about it is that it doesnÂ’t make sense?
which, if that's Cockney rhyming slang, could be blasphemous - YIKES!

Peter Duncanson, UK
(in alt.english.usage)