This is what Blackstone had to say on the subject:
[E]very member, though chosen by one particular district, when elected and returned serves for the whole realm. For the end of his coming thither is not particular, but general; not barely to advantage his constituents, but the common wealth; to advise his majesty.... And therefore he is not bound, like a deputy in the united provinces, to consult with, or take the advice, of his constituents upon any particular point, unless he himself thinks it proper or prudent so to do.And this is Edmund Burke, in his Speech to the Electors of Bristol (1774):
Certainly, Gentlemen, it ought to be the happiness and glory of a representative to live in the strictest union, the closest correspondence, and the most unreserved communication with his constituents. Their wishes ought to have great weight with him; their opinions high respect; their business unremitted attention. It is his duty to sacrifice his repose, his pleasure, his satisfactions, to theirs — and above all, ever, and in all cases, to prefer their interest to his own. But his unbiased opinion, his mature judgment, his enlightened conscience, he ought not to sacrifice to you, to any man, or to any set of men living. These he does not derive from your pleasure — no, nor from the law and the Constitution. They are a trust from Providence, for the abuse of which he is deeply answerable. Your representative owes you, not his industry only, but his judgment; and he betrays, instead of serving you, if he sacrifices it to your opinion.
My worthy colleague says, his will ought to be subservient to yours. If that be all, the thing is innocent. If government were a matter of will upon any side, yours, without question, ought to be superior. But government and legislation are matters of reason and judgment, and not of inclination....
To deliver an opinion is the right of all men; that of constituents is a weighty and respectable opinion, which a representative ought always to rejoice to consider. But authoritative instructions, mandates issued, which the member is bound blindly and implicitly to obey, to vote, and to argue for, though contrary to the clearest convictions of his judgment and conscience — these are things utterly unknown to the laws of this land, and which arise from a fundamental mistake of the whole order and tenor of our Constitution.
Parliament is not a congress of ambassadors from different and hostile interests, which interests each must maintain, as an agent and advocate, against other agents and advocates; Parliament is a deliberative assembly of one nation, with one interest — that of the whole — where not local purposes, not local prejudices, ought to guide, but the general good, resulting from the general reason of the whole. You choose a member, indeed; but when you have chosen him, he is not member of Bristol, but he is a member of Parliament. If the local constituent should have an interest, or should form an hasty opinion evidently opposite to the real good of the rest of the community, the member for that place ought to be as far as any other from any endeavour to give it effect.