parliamentary private secretary 
noun
(In the UK) a Member of Parliament assisting a government minister.A Prime Minister appoints over a hundred ministerial posts covering Cabinet, non-Cabinet, and junior ministers, and parliamentary private secretaries....
- Mr Stringer has put down an early day motion in the Commons with St Helens MP Dave Watts who used to be the parliamentary private secretary to transport minister John Spellar before the reshuffle.
- As many as 10 parliamentary aides or parliamentary private secretaries are threatening to do likewise.