Prince Harry has revealed the one job he could not bring himself to do during his stint as a teenage jackaroo in Outback Queensland – castrating calves.

Between leaving Eton College and joining the British Army the Duke of Sussex spent nine weeks on Tooloombilla Station as a 19-year-old in late 2003.

The 16,000 hectare cattle property 150km northwest of Roma was owned by Annie and Noel Hill, who had been friends of his late mother Diana, the Princess of Wales.

Annie Hill had had been Diana’s roommate when she was first courted by Harry’s father, then the Prince of Wales and now King Charles III. Mr Hill’s father had been a professional polo player who taught Charles the sport.

Harry writes in his new memoir Spare that Charles discouraged him from attending university after leaving school and instead suggested he take a gap year.

‘It was no secret, he tactfully told me, that I was not “the intellectual of the family”,’ Harry writes in Spare. ‘He didn’t mean to hurt me. Still, I shuddered.’

Harry had planned to spend six months on an Australian farm, far from the prying eyes of the paparazzi, and six months in Africa where he would continue his mother’s charity work.

When the young prince arrived at Tooloombilla – twice the size of his family’s Scottish estate Balmoral – he soon realised it would be nothing like Eton.

The Hills had three children, Nikki, Eustie and their eldest son George, who – despite being Harry’s age – would become his boss, mentor and tutor.

The first change in his circumstances that struck Harry was the searing heat. Coming from a cool climate he was now forced to work in furnace-like conditions.

Fortunately, Harry was allowed to stay in the Hills’ main house, which he describes as a lovely little bungalow, while his bodyguards were stuck in an outbuilding on the edge of the station.

Harry writes of feeling awkward at dinner when conversation inevitably turned to his mother, who had been killed in a Paris car crash six years earlier.

A typical working day started hours before dawn when Harry and George would complete as many tasks as possible before sunrise.

The pair would then saddle up and head out to muster cattle, which sometimes did not end well if a beast broke off from the herd.

‘From time to time, in the heat of the chase, you would fall out of your saddle when you hit a low branch and, sometimes, you would be knocked unconscious,’ Harry writes.

Upon recovery from such a fall, Harry would check his body for fractured bones or internal bleeding. Some days the only person he would see on the station was George.

While Harry threw himself into station life there was one job he refused to do.

‘The only job that I did not take care of, the only difficult task that I avoided, was cutting their testicles,’ he writes in Spare. ‘Every time George pulled out that shiny long blade I would throw up my hands. No way, man, I can’t. You do it.’

At the end of a long day, Harry and George would eat dinner then sit on the verandah rolling cigarettes and downing cold beers. They were in bed by 8.30pm.

Harry writes that he lost so much weight from the exhausting work he felt like he was wasting away and began looking and sounding more like George the stockman than an English prince.

Harry’s hair had never fully recovered after it had been shaved off by his mates at Eton. Some strands stood up and others stuck to his head.

After a trip to Taronga Zoo while attending a Rugby World Cup game in Sydney the prince posed for a picture with an echidna which had been named ‘Spike’ due to its quills.

George saw the photograph and thought Harry looked like the echidna and dubbed him Spike, as did his bodyguards.

Harry began calling himself Spike on the walkie-talkie when talking to his security detail, some of whom had T-shirts made that said ‘Spikes 2003’.

Eventually, the name even caught on with Harry’s friends and some of his family back in England.

A Facebook profile which existed from 2008 to 2012 under ‘Spike Wells’ and believed to be used by the prince had some of Britain’s wealthiest young people as friends.

Harry’s intended stay on Tooloombilla was cut short by the appearance of paparazzi. In December police found an intruder on the station, and two more got in the next day.

Not wanting to expose the Hills to an invasion of their privacy, Harry flew home to England, arriving days before Christmas.

‘I have had a great time working out here, meeting people and learning a bit about how to be a jackaroo,’ Harry said in a statement at the conclusion of the trip.

‘And of course the rugby was absolutely fantastic. It’s a great country.’