Mountbatten was a British individual involved in the Partition of India.
When Prem accused the British of "carving [his country] up slapdash in six weeks," the Thirteenth Doctor noted she would pass his thoughts on to Mountbatten. (TV: Demons of the Punjab)
Behind the scenes
In the real world, Louis Mountbatten, 1st Earl Mountbatten of Burma, was the last Viceroy of India during British rule, and the first Governor-General of independent India, heavily involved in the partition.