The IRA murder of Lord Mountbatten is curtain raiser to season four of The Crown

The 79-year-old, godson to Queen Victoria and great uncle to the Prince of Wales, was assassinated by the paramilitaries, while holidaying at Classiebawn Castle in Co Sligo in August 1979.

A bomb was planted on his fishing boat and he was pulled alive from the water by nearby fishermen, but died from his injuries before being brought to shore.

This shocking event is to be a central part of the first episode of season four as showcased by the official trailer which Netflix has just released .

The opening clips show the tensions in Northern Ireland at the time and reveal the impact Mountbatten's murder had on the election of the Iron Lady.

The new trailer looks at the boiling unrest in Northern Ireland and also depicts the intense first meeting between the Queen and new Prime Minister Margaret Thatcher, portrayed by Sex Education star Gillian Anderson.

Thatcher wastes no time clarifying that she is actually six months older than her majesty, sparking a power struggle as the two discuss the Prime Minister’s troubled time in office.

“Joblessness, recession, crises… It’s a dangerous game to make enemies left, right and centre,” Queen Elizabeth warns.

Thatcher goes on to assure the monarch that she is perfectly “comfortable” with having enemies, and sets her site firmly on resolving the tensions in Northern Ireland.

The Crown season four is released on 15th November.