You're in luck! I've recently borrowed a book,
The Penguin Dictionary of Surnames, 2nd ed. You're getting good information... here's the full citation I"ve got:
Quote:Longmoor, Longmore, Longmuir L (note: this means a Local name as opposed to an occupational name) meaning long moor OE (Old English) but confused also with long mere/pool OE
From that, and having read other parts of this book, I'd say that the name is not from Scotland -- Scottish names in this book say so and report a Gaelic origin -- though it could definitely have come from the borderlands. There are also moors in the southern part of England -- I don't know if any are long.
The note about possibly being from long mere is also interesting. There is a common surname, Longmire, meaning long bog, referring to a place in Westmoreland and a Westmoreland surname.
This book frequently refers to an older original work of British surnames called
Homes of Family Names in Great Britain, by H. B. Guppy, London 1890, that may give you some interesting information.
Check Google using Longmoor -- I did and found about 1500 entries. I checked one and found this cool bridge...
Longmoor Bridge, which is part of the Grantham canal.
(From the website) "This delightful canal runs for 33 miles from its junction of the River Trent at West Bridgford, through the attractive Vale of Belvoir to the market town of Grantham."
Now don't you feel better about your "lame name"?
Grantham Canal Website