Who was the prime minister of Britain who introduced communal award?

The Communal Award was introduced by the Prime Minister Ramsay Macdonald. 

The reason why Macdonal introduced the award was because he considered himself as a ‘friend of the Indians’ and that this award would resolve the issues that beset India at the time.

For further reading check the following articles:

• Morley-Minto Reforms
• Government of India Act 1919