The quotation usually attributed to Churchill is…

“The quotation usually attributed to Churchill is, ‘If you’re not Liberal when you’re 25, you have no heart. If you’re not Conservative when you’re 35, you have no brain.’ However, the attribution is false. There is no record of Churchill ever speaking these words, and it is highly unlikely that he would have because Churchill himself did precisely the opposite. He entered politics as a Conservative and was a Conservative at age 25. He switched to the Liberal Party at age 29 and was a Liberal at age 35. (He returned to the Conservatives at age 49.)”

Though there may be some doubt about this attribution, it nonetheless has value in sentiment.