<Tr> <Td> Twenty - five pence </Td> <Td> No standard reverse design </Td> <Td> 38.61 mm </Td> <Td> 2.89 mm </Td> <Td> 28.28 g </Td> <Td> Cupronickel </Td> <Td> Milled, with variable inscription </Td> <Td> 1972 (commemorative, not in general circulation) </Td> </Tr> <Tr> <Td> Fifty pence * </Td> <Td> Britannia and lion </Td> <Td> 27.3 mm </Td> <Td> 1.78 mm </Td> <Td> 8 g </Td> <Td> Cupronickel (75: 25) </Td> <Td> Smooth, Reuleaux heptagon </Td> <Td> 1997 </Td> </Tr> <Tr> <Td> Various commemorative designs </Td> <Td> 1998 </Td> </Tr> <Tr> <Td> Segment of the Coat of Arms of the United Kingdom </Td> <Td> 2008 </Td> </Tr>

How many different types of old pound coins are there