Chris Patten, the final governor of Hong Kong, and former Labour minister Catherine Ashton have been appointed by the King to the Order of the Garter.

Charles has announced that Lord Patten of Barnes, a former Conservative MP and who served as governor of Hong Kong from 1992 to the handover to China in 1997, has been appointed to be a Knight Companion of the Most Noble Order of the Garter.

Former Labour minister and European Union diplomat Baroness Ashton of Upholland was appointed to be a Lady Companion of the Most Noble Order of the Garter.

The announcements for the oldest and most senior order of chivalry in the country are made on St George’s Day (April 23) – the patron saint of the order.

In a statement, Buckingham Palace said: “His Majesty The King has been graciously pleased to appoint the Right Honourable the Baroness Ashton of Upholland GCMG to be a Lady Companion of the Most Noble Order of the Garter and the Right Honourable the Lord Patten of Barnes CH to be a Knight Companion of the Most Noble Order of the Garter.”

The appointment is in “the King’s gift” and is in the same category as the Order of the Thistle, the Order of Merit and the Royal Victorian Order, the statement added.

According to the royal website, The Order includes The King, who is Sovereign of the Garter, several senior members of the royal family and 24 knights chosen in recognition of their work.

It states: “Knights of the Garter are chosen personally by the Sovereign to honour those who have held public office, who have contributed in a particular way to national life or who have served the Sovereign personally.

“These have included Marshal of the RAF, Lord Stirrup, and former prime ministers Sir John Major and Sir Winston Churchill.”

Baroness Ashton served as parliamentary under-secretary of state in the Department for Education and the Ministry of Justice between 1999 and 2007.

She also served as Leader of the House of Lords and Lord President of the Council as well as diplomatic roles including British European commissioner and commissioner for trade in the European Commission, vice-president of the European Commission and as the EU’s first high representative of the union for foreign affairs and security policy.

She contributed towards negotiating a peace settlement between Serbia and Kosovo, and bringing about the Iran nuclear agreement.

Baroness Ashton was appointed a Dame Grand Cross of the Order of St Michael and St George in the 2015 New Year Honours for services to international diplomacy, has served as the Order’s King of Arms and is currently Chancellor of the Order.

Lord Patten of Barnes was first elected as an MP in 1979 and served across government for more than two decades, including as secretary of state for the environment and chancellor of the duchy of Lancaster, as well as Conservative Party chairman.

He also led the Independent Commission on Policing for Northern Ireland and served as European commissioner for external relations from 1999 to 2004, and was chairman of the BBC Trust between 2011 and 2014.