Who are the Windrush generation? A British scandal explained

File photo of Jamaican immigrants being welcomed by RAF officials from the Colonial Office.

London (CNN)On Monday, Britain celebrates Windrush Day, honoring a generation of Caribbean immigrants who moved to the UK in the late 1940s at the invitation of the government.

In recent years though, the British government's treatment of those individuals -- known as the Windrush generation after the Empire Windrush passenger liner that brought some of them across the Atlantic -- and their descendants has been the subject of a massive scandal.

Who are the Windrush generation?

    The people who became known as the Windrush generation were invited to Britain to lay roads, drive buses, clean hospitals and nurse the sick, helping to rebuild the country after the devastation of World War II.
      They first arrived aboard the Empire Windrush in June 1948, landing at Tilbury Docks, about 20 miles from London. These voyagers -- many of them from Jamaica -- were the first large group of Caribbean migrants to arrive in the UK.
      They came to symbolize the seismic demographic changes in Britain that started after World War II and continued into the late 20th century, as hundreds of thousands of people arrived from former British colonies, known as the Commonwealth.

      What was the scandal about?

      File photo of the Empire Windrush ship.
      The Windrush generation migrants arrived in Britain legally. Until a new immigration law came into force in 1973, Commonwealth citizens and their children had the automatic right to live and work in the UK. Many did so, without any need for additional documentation.
      In late 2017, however,