After spending the last hour tracking down a problem with my large
query, I have isolated this simple test case:

SELECT 1 AS Test1, 2 As Test2
UNION ALL
SELECT 2 As Test2, 1 AS Test1

Produces:

Test1 Test2
1 2
2 1

This looks very obviously wrong to me, but just wanted to check it's
not me misunderstanding some kind of usage rules with UNION or
something.

Cheers,
Jeremy