They say a firm handshake is a sign of strong leadership.

So from the evidence of this picture, Prince William was left in no doubt that Narendra Modi was prime minister of more than a billion people.

Such was the strength of Mr Modi’s embrace when he greeted the Royal couple, the Duke of Cambridge was left with a clear palm print on his right hand.

Making a mark: Indian Prime Minister Narendra Modi leaves a palm print on Prince William's right hand (circled) after giving him a very firm handshake when he greeted the Royal couple on their tour of India

Making a mark: Indian Prime Minister Narendra Modi leaves a palm print on Prince William’s right hand (circled) after giving him a very firm handshake when he greeted the Royal couple on their tour of India

Impressive handshake: Mr Modi's palm print can be seen for some seconds as they pose for photographs

Impressive handshake: Mr Modi’s palm print can be seen for some seconds as they pose for photographs

It could simply have been over-enthusiasm.

But it may also have been a show of authority, suspecting that Prince William was about to address the thorny issue of Britain’s embattled steel industry over their lunch together.

Whichever it was, he certainly left an impression.

The meeting with Mr Modi and senior figures in his government was a last-minute addition to the royal tour schedule.

Prince William raised the steel crisis just a fortnight after Indian firm, Tata Steel, announced it was selling its British operation with the possible loss of 40,000 jobs.

The Duke of Cambridge shakes hands with Prime Minister Narendra Modi at Hyderabad House in New Delhi

The Duke of Cambridge shakes hands with Prime Minister Narendra Modi at Hyderabad House in New Delhi

A senior royal source revealed afterwards that the subject was discussed at the lunch, which was also attended by the Duchess of Cambridge.

‘The pressures facing steel manufacturers in the UK and India were discussed,’ said an aide, although he refused to be drawn on the finer detail.

‘It was a very positive and productive occasion,’ they added.

It is the second time this year that William, 33, has delved into politics. In February he appeared to make a speech signalling his support for staying in the EU.

The meeting with Mr Modi and senior figures in his government was a last-minute addition to the royal tour

The meeting with Mr Modi and senior figures in his government was a last-minute addition to the royal tour

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