MP's to declare all income & property that generates from the European Union.

It would explain where loyalties may lay within the UK Political Parties, when voting on European matters

The House of Commons has a Code of Conduct for MPs. MPs are already required to register and declare financial interests, and to avoid conflicts of interest, so we're not sure exactly what further action you'd like to see.

You can find the Code of Conduct for the House of Commons here:

https://www.parliament.uk/mps-lords-and-offices/standards-and-financial-interests/parliamentary-commissioner-for-standards/code-of-conduct-and-rules-of-the-house/