<Tr> <Td> 21 </Td> <Td> Attlee! Clement Attlee </Td> <Td> 6 years, 92 days </Td> <Td> </Td> <Td> Labour </Td> <Td> 1945 </Td> </Tr> <Tr> <Td> 22 </Td> <Td> Cameron! David Cameron </Td> <Td> 6 years, 63 days </Td> <Td> </Td> <Td> Conservative </Td> <Td> </Td> </Tr> <Tr> <Td> 23 </Td> <Td> Russell! Lord John Russell </Td> <Td> 6 years, 11 days </Td> <Td> </Td> <Td> Whig </Td> <Td> 1864 </Td> </Tr> <Tr> <Td> 24 </Td> <Td> George! David Lloyd George </Td> <Td> 5 years, 317 days </Td> <Td> </Td> <Td> Liberal </Td> <Td> 1916 </Td> </Tr>

Who had the longest tenure as prime minister