Given he is one of the most outspoken environmentalists of modern times, it seems a strange decision that Prince Charles flew in a helicopter to travel 125 miles to make a speech about lowering aircraft emissions.

It might appear to be the kind of hypocrisy with which Harry and Meghan were charged when they chose to use a private jet last summer after campaigning on climate change.

Clarence House, Prince Charles' office, insists a road or rail journey to Cambridge was not possible given where the Prince had to be at the beginning and end of the day when he made the visit to Cambridge.

But you might ask if those demands on his time and geographic location should be re-engineered if they necessitate air travel to cover relatively short distances in the UK.

Credit: PA

The Prince of Wales departed from his home in Highgrove in Gloucestershire on Thursday for the visit to the Whittle Laboratory where they carry out research into the development of ultra-low emission aircraft and low carbon power generation.

Had the Prince travelled by car, via the M4 motorway, his carbon footprint would have been around 0.05 tonnes for the 150 mile journey.

Studies show helicopter travel is up to five times more polluting per mile travelled.

So why would such a keen environmentalist travel by such a polluting form of transport?

The Prince does not choose his mode of transport, it is arranged for him based on his diary commitments and timings.

Royals often carry out work on behalf of the government, like official overseas visits, and therefore they cannot always control the distances they are required to travel.

Had his team opted for a road or rail journey, they say Prince Charles would have had less time in Cambridge promoting the work on sustainability by the Whittle Laboratory.

It is true that someone as influential as the Prince of Wales, or Sir David Attenborough, will have to travel to promote their work and spread their messages on climate change and the threat to our planet.

By contrast, Harry and Meghan's private jet flights last summer, were for their holidays, not official work.

Prince Charles focused on sustainability during his Davos speech. Credit: AP

The Prince recently spoke at the World Economic Forum in Davos on climate change to promote his new Sustainable Markets Council.

He took a flight en route to his official visit to Israel and the Occupied Palestinian Territories, which was, we are told, a deviation of just 25 nautical miles.

He also chose to drive from the airport to the conference in an electric car rather than take a helicopter.

When such care had been taken in Davos to avoid any accusations of hypocrisy, it seems to have been a bit of an oversight by his office not to take the same precautions on the Prince's travel plans for his visit to a low carbon research laboratory in Cambridge.

The Prince does have many demands on his time, and nobody can criticise his passion and commitment to the campaign against climate change - which began in the 1970s long before anyone else had recognised the damage we were doing to the planet.

In London, for example, he has swapped his diesel powered car for an electric one.

But it is a lesson to Clarence House to better prioritise the carbon footprint of the Prince's travel plans.

For prominent campaigners on any subject, authenticity counts for a lot - and the Prince's commitment to the environment is authentic.

But it can be undone all too easily by clumsy travel plans which leave him open to the charge of hypocrisy.