A neutral, non-partisan role an MP is supposed to fulfill for all constituents
Limits the tyranny of the majority - ALL constituents if they want to be reelected
Delegate model
MPs should do what the constituents want them to do e.g. 80% of MPs wanted to remain but 77% voted to enact Article 50
Trustee/Burkean model
Constituents elect their representatives as trustees, have autonomy to deliberate/act as they see fit e.g. MP Creagh voted against enacting Article 50 even though 66% of her constituents wanted to leave
Methods
BBs can lobby a minster proposing an unpopular decision, listen to grievences e.g. Cates had 300-400 emails, attend important events and visit from WM
Only applies to Commons - Lords have no formal constituency
Constituency interests can be at odds with party interests and MPs usually abandon party loyalty