Was Lady Scotland's employment of her Tongan servant knowingly illegal? No, I am sure not. Should she resign? Yes.
Why should she resign? NOT because she inadvertently broke the letter of a law whilst acting reasonably and in good faith - but because she was a key player in this Government's deliberate imposition of (perhaps unreasonably) onerous requirements on ANYONE employing an immigrant. When this legislation was going through, small business representatives said that the strict requirements to check and copy all paperwork etc. were unnecessarily burdensome, and would be difficult for small businesses or individuals to comply with in practice. Lady Scotland's - the Government's - reply was clear: the onus was on the employer, they must comply and the mere burden of compliance was not an excuse. Ignorance of the detail of the law was not, of course, an excuse. Acting reasonably in good faith was not an excuse.
So the Government can take one of two honourable courses - (a) admit that such legislation imposed an unreasonable burden on individuals and small businesses, and amend it accordingly, OR (b) maintain their stance, and take the appropriate action against Lady Scotland, who must also, of course, resign.
What they cannot in honour do is maintain the strict rules for the rest of us with no excuses allowed, but excuse Lady Scotland. That is untenable. That is dishonest. That is wrong.