He ranks as one of the most influential figures in Scottish and British political history.

Now thousands of items from the family archive of former prime minister Arthur Balfour have been bought by National Records of Scotland (NRS) for half a million pounds.

The collection includes letters from Winston Churchill, a photograph of Balfour at the Old Course in St Andrews, and the controversial 1917 Balfour Declaration, which he authored, which announced Britain’s support for the establishment of a “national home for the Jewish people” in Palestine.

Balfour, 1st Earl Balfour, was the prime minister from 1902 to 1905, and later, as Foreign Secretary, he was one of the principal British delegates at the Versailles peace conference in 1919 which negotiated the peace treaty following the First World War.

The items cover 20 metres of shelving space and were bought for just over £500,000.

Head of private records for NRS Dr Alan Borthwick said the collection was the first major one he had seen in the last decade – the previous one being from the Melville family.

“It is not often that we get these opportunities,” he said.

“In my 33 years working at NRS, I think this is probably the sixth major collection we’ve bought, and the first one in about 10 years.

“We’re very pleased that our senior staff were able to agree that this was a pre-eminent collection on a local, national and international scale, and therefore was worth our while.”

Admiring the new collection, Dr Borthwick said the Balfour family were very well-connected in scientific, artistic and political circles.

It means there are letters from scientists such as Charles Darwin; artists such as Sir Edward Burne-Jones, Sir Philip Burne-Jones and Augustus John; and suffragette campaigners Millicent Fawcett and Dame Ethel Smyth.

“The collection has got such a widespread interest for students of politics, and social life in Scotland and also the UK in the late 19th to early 20th century,” he said.

“We are very happy to keep the collection available in our research room and we are hoping to be able to expand our knowledge of it.”

The collection had previously been on loan to NRS from the Balfour family since the 1960s until they agreed to sell it earlier this year.

The documents are made available on request to be viewed in the NRS public search room in General Register House, Princes Street, Edinburgh.

Culture Minister Neil Gray said: “This purchase safeguards a remarkable collection which offers insights into the life of an influential Scottish family over a huge period of history.

“The public ownership of the Balfour archive not only ensures that it is preserved whole and in Scotland forever, but that the public and researchers have the opportunity to see and study it.

“I look forward to finding out more about the highlights in this collection once National Records of Scotland have carried out further detailed research on its content.”

Michael Brander and Lord Balfour, speaking on behalf of the family, said: “Our forebear, Arthur James Balfour, was at the centre of many pivotal events over his remarkable life and the dilemmas he faced, including Irish home rule, free trade and unwarranted aggression in Europe, still resonate today.

“We are delighted that his papers have found a permanent home at the National Records of Scotland for future scholarship.”