Dr Alf is correct and the article is factually wrong in every respect.
Dyer, in the inquiry which followed the massacre, was admonished for giving insufficient time between his warning and the orders to fire if the people didn’t disperse. This was because some of the youngest victims were under the age of 4.
The British Empire came to an end, in its final form, with the independence movement in India, instigated by Ghandi and in the botched separation of India and Pakistan by Mountbatten, which resulted in the deaths of nearly 50 million people in Hindu versus Muslim religious strife.
After these events, we had independence movements in Africa, the Kenyan and Cyprus “emergencies”, which ended in 1964 and 1956 respectively – both decades after 1919.
The British Empire, in reality, metamorphosed into the Commonwealth, and the UK positioned stooges such as Robert Mugabe in Zimbabwe and Jomo Kenyatta in Kenya to do our bidding, whilst supposedly operating as independent Republics.
The Monarch is head of the Commonwealth and, using delegated authority through her Governors General, has the power to fire Prime Ministers and approve or reject budgets. Two Australian Prime Ministers were fired in this way and Sir John Major, in his memoirs and on the BBC, said that the New Zealand Prime Minister was in front of him awaiting an audience with the Queen to have his budget approved.
Robert Mugabe, whilst in the bush, fighting the Rhodesian SAS, had his life saved by a tipoff from MI6 so from that point on owed his life and allegiance to the UK.
The old “Empire” has gone but the new hidden one is very much in evidence, although money generated from it never reaches UK shores.