The heat got turned up in the BBC MasterChef kitchen on Wednesday and Thursday, when London-based Irish contestants Alison O'Reilly and Shauna Kelly faced the dreaded restaurant service and invention test challenges.

“My approach is to do exactly what I’m told, and not mess it up,” said Dubliner O’Reilly as she prepared to cook Iberico pork with grilled calamari, chorizo jam and tomato puree with pressed Asian pear and fennel salad, on the lunch service at Ormer Mayfair restaurant.

It was a tactic that worked for the marketing consultant, who sailed through the test. “I absolutely loved the restaurant. It’s tough work but extremely exhilarating. I loved experiencing the pace, the precision, the passion for food. It’s wonderful to be surrounded by all of that and to be able to watch and learn from professionals. I took away a lot from it,” she told the Irish Times.

But in the invention test that followed, when the contestants were asked to present one restaurant-worthy plate with ingredients chosen from a well-stocked larder, the 30-year-old’s steely composure faltered for the first time in the series.

‘Flustered’

"You don't look your usual calm self; you look a little flustered," judge Gregg Wallace observed, not very helpfully. "I may have given myself a little bit too much to do," she replied, showing admirable restraint.

A little bit? Venison and beetroot – roasted, pureed and made into crisps – with potato and goat’s cheese ravioli and goat’s cheese mousse, sounded like a lot to get through.

Co-judge JohnTorode reckoned that O'Reilly wasn't sure the cut of venison she was using was saddle, judging by her cooking plan for it. And when the final plate was presented to Edinburgh chef Tom Kitchin, a surprise addition to the judging panel for the night, all he could say about the practically pulsating chunk of meat was "I'm afraid it's blue, and not many people like blue venison."

“I actually love venison and I’m just annoyed with myself I didn’t do it properly. It’s infuriating. I never, even when practising at home, make mistakes like that,” she said in the tense pre-result interview.

"I knew what a saddle of venison was and recognised it, but had never cooked it before", she told The Irish Times. "I knew I was in a bit of trouble."

Luckily, there was someone with an even worse plate to account for, and as aerospace engineer Fumbi was shown the door, O'Reilly's shoulders dropped in relief, and she could look forward to cooking again.

Invention test

On Thursday, the second batch of six knockout week contestants cooked at Roux in Parliament Square, and also faced an invention test. Sligo-born Shauna Kelly, who has been living in London for 14 years, earned host chef Steve Goves’s respect for her cooking of his barbecued Iberico pork with spelt risotto, carrot ketchup and roasted onion. “You’re doing a great job, really nice and precise.”

“I’m loving this, I could be doing this all day,” said the very likeable former advertising director.

But Kelly’s bubble burst in the invention test. After saying that she preferred cooking savoury dishes, but was doing a dessert this time, and was “a bit scared”, the warning bells began tinkling. They reached a crescendo when she introduced her dish to Torode and Wallace.

Poached pear with walnut crumb, treacle ginger cake and red wine granita sounded ... interesting. But with beetroot crisps and blue cheeses mascarpone? That’s not inventive, that’s a recipe for disaster in a MasterChef knockout round.

“Wow” Torode said, in a manner that suggested he’d rather eat his shoe than this dessert.

Tom Kitchin, back to give his expert verdict again, was also unconvinced. “I’m really sorry, it didn’t work for me,” he said, sounding genuinely apologetic.

“It just didn’t work, there’s too much going on, it’s a cacophony,” Torode decreed, sealing the Hampstead mother of one’s departure.

Exit interview

“I’m deflated and upset,” she said in her exit interview. But she also managed to find a positive. “I’d love to have my own boutique catering company and it’s really given me the confidence to pursue my dream.”

On Thursday she told The Irish Times that she has moved ahead with that dream and turned it into reality.

“Never did I think I’d get the chance to wear chef whites and cook in a professional kitchen, especially one like Roux. The attention to detail, the buzz, the precision, the heat ... it was everything I imagined and more.

“It has now given me the impetus and courage to start my own catering business in London, called HOMEmade Hampstead. Competing in MasterChef has been so rewarding and changed my life for the better. I urge anyone who is passionate about food to apply and just enjoy the ride.”

Alison O’Reilly’s rollercoaster ride continues on Friday evening when knockout week comes to an end, with the final 10 cooking their “showstopper dish” in the hope of a place in next week’s semi-finals.