LONDON (Reuters) -Prince William said Britain was a better place thanks to the "Windrush generation", as the nation on Thursday celebrated the 75th anniversary of the arrival of the first post-World War Two Caribbean migrants.

On 22 June 1948, the Empire Windrush ship arrived at Tilbury Docks in Essex, east of London, bringing the first of hundreds of thousands of people who came to Britain between 1948 and 1971 to help rebuild the country after the war.

To mark the anniversary, church services, processions and exhibitions to pay tribute to the cultural contribution of the "Windrush generation" will be held in London and across the country, with the events starting at the Tilbury Docks.

"Their contributions to Britain cannot be overstated," Prince William, King Charles' eldest son and heir, said in a video message.

"We are a better people today because the children and the grandchildren of those who came in 1948 have stayed and become part of who we are in 2023. And for that we are forever grateful."

Many of the events will also acknowledge the prejudices the Windrush arrivals and their descendents have had to overcome.

Those who came on the Windrush, a German-built ship which the British captured as a prize of war and renamed after an English river, spent their first nights in London sleeping deep underground in a shelter beneath Clapham South underground station.

They then found jobs in the National Health Service or on public transport systems, but many were victims of racism, with discrimination continuing to the present day in some parts of life.

In 2018, Britain apologised for its "appalling" handling of the Windrush generation, after a tightening of immigration policy meant thousands were denied basic rights despite having lived in Britain for decades, and dozens were wrongly deported.

Event organisers said the 75th anniversary was seen as a moment to reflect on that wrongdoing, as well as to celebrate the migrants' contribution to British society.

"We know they experienced hardships," William said. "But they also experienced joy; and life did indeed change for them and their families."

His father has commissioned 10 portraits of 10 members of the Windrush generation as part of the celebrations. These will go on display at Buckingham Palace later this year.

"It is, I believe, crucially important that we should truly see and hear these pioneers who stepped off the Empire Windrush at Tilbury in June 1948," the monarch said.

Among Thursday's events will be a procession in Brixton, the south London area where many of the migrants made their home, and services at Southwark Cathedral in London and at Windsor Castle, which the king will attend.

(Reporting by Sarah Young and Michael Holden, additional reporting by Muvija M; Editing by Sharon Singleton)