<Tr> <Th> Leader </Th> <Td> Ernest Manning </Td> <Td> Peter Lougheed </Td> <Td> Michael Maccagno </Td> </Tr> <Tr> <Th> Party </Th> <Td> Social Credit </Td> <Td> Progressive Conservative </Td> <Td> Liberal </Td> </Tr> <Tr> <Th> Leader since </Th> <Td> May 31, 1943 </Td> <Td> 1965 </Td> <Td> January 28, 1967 </Td> </Tr> <Tr> <Th> Leader's seat </Th> <Td> Strathcona East </Td> <Td> Calgary - West </Td> <Td> Lac La Biche </Td> </Tr>

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