those who do something before becoming an MP, local councillors for one, those who work for MP's, you don't just generally fess up on the day and say here i am, without some form of knowledge of the political arena.
just because he has famous parents, why haven't we heard before he has political aspirations, following in daddy's footsteps. Canvassing for his party, working on their behalf, many of the current crop worked in the political forum before becoming MP's.