Economical with the truth is popularly used as a euphemism for deceitful, whether by volunteering false information (i.e., lying) or by deliberately holding back relevant facts. More literally, it describes a careful use of facts so as not to reveal too much information.
A similar expression appeared in Mr. Punch's History of the Great War, published in July 1919:
| “ | Lord Kitchener has been charged with being "very economical in his information" vouchsafed to the Lords...[1] | ” |
The modern phrase entered popular usage after it was used by the British then-Cabinet Secretary Robert Armstrong during the Spycatcher trial in 1986. It derives from Edmund Burke:[2]
| “ | Falsehood and delusion are allowed in no case whatever: but, as in the exercise of all the virtues, there is an economy of truth. It is a sort of temperance, by which a man speaks truth with measure that he may speak it the longer.[3] | ” |