She wore a Games pin badge every single day, a statement about her dream to be on the team. A unique three European junior cross-country titles and world junior 1500 metres gold confirmed she was on track. So did Commonwealth 1500m bronze in Delhi. By spring this year the Olympic 5000m qualifying time was secure.
However, at the end of June, her first step in the 5000m at the European Championships was her last – the moment when the dream crashed and burned.
Olympic 5000m selection had seemed such a formality that she also tried for a 1500m place. All this seemed miraculous, given that a metal plate and screws had to be inserted in an ankle after a cross-country accident in February 2011. Yet she seemed to have overcome it all, until the ankle and her world fell apart in Finland.
The UK Athletics performance director Charles van Commenee insisted on a time trial just a week after Twell had run 4:07 for 1500m. "The torment leading up to the Europeans was pretty traumatic," she said. "I walked off after that time trial with the ankle throbbing. I was limping even walking on to the flight to Helsinki, and had to practice where the anaesthetic would be injected on race day.
"I so wanted to race there, but when I put on my spikes it was throbbing. All my rivals were doing strides. I was hobbling, hoping adrenaline would take over when the gun went, but I took one stride and it was like a lame leg, and I walked off the track. I know that time trial did the damage."
Before-and-after scans seemed to prove it, the second revealing a new stress fracture. Surgery to remove the metal ruled out the Games. So she watched the race in which she herself should have run on TV.
She is exquisitely positive. There is no hint of self-pity as she talks of her Commonwealth Games aspirations, the Scottish recruits to her training group (Lenny Waite and Beth Potter), and their podium ambitions for Glasgow 2014. "At last my ankle feels like it belongs to me again," she says, "and I am in a much better place. I was totally deflated for two weeks, but the turning point was when Dai Greene [athletics team captain] referred to me in his team speech."
Green told how Twell had worn her pin every day since 2005, but was absent despite committing everything, and urged those who were there to make the most of it. "So I feel I contributed on a spiritual and motivational level. That turned the whole thing round for me, and I embraced the summer. I watched the Games, and it was the perfect inspiration I needed after quite a rough time.
"I'm not bitter at all. It's pursuit of the goal that yields most happiness. So I'm looking to 2014 with the same force and passion. There is a point you want to have redemption from, but I am not trying to chase anything, or compensate. I am in tune with where I want to be in life. Eventually it will all be worthwhile."
Only last weekend did she begin training again, on Arthur's Seat, a tentative session which she declines to dignify by calling it running. "I just did a little shuffle. It will go from a shuffle to a trot, then jogging and finally running. I am moving from trotting to jogging now, slowly weaning myself back. I gave my all before the Olympics, and my ankle didn't like it. I went to Kenya, training in Iten with Freya [Murray the Olympic marathon runner] and Beth [Potter, another Scottish internationalist]. I needed treatment every day on the massage bed. It was absolute agony. I was in tears as they worked on the scar tissue round the metal work."
There was nowhere more appropriate to begin again. Holyrood is where Twell made her home debut for Scotland in 2010, after switching allegiance from England (her mum, Isobel, is from Paisley). She took part with her ultra-runner boyfriend in the Speed of Light festival on the slopes, went to events at the Festival Fringe, and fell in love with the Highlands, walking the West Highland Way. "We only did 80 miles," she says apologetically. "It was breathtaking, but we missed out on the last 14 miles, from Kinlochleven."
It transpires she did this in three days, carrying a tent – the ankle was on the way to recovery. She and her mentor, former marathon runner Mick Woods (Britain's most consistently successful women's endurance coach) have been joined at St Mary's College in London by Commonwealth steeplechaser Waite and Milngavie's Potter. "I met Lenny in Delhi, and Beth in Kenya. Now they've both joined us."
The group also includes former Scottish champion Kris Gauson, plus the prodigious Emily Pidgeon, also in rehab.
Twell has been helping the Sport Partnership Trust on a whistle-stop tour in Scotland. "This is after a lot of reflection in the last few months," she says. "There is no dilution of competitive ambition. Running is the most important priority, but as an elite athlete, you are so driven, so focused, that you kind of stop a normal life. When you get injured and aren't running, you wonder about your identity. So I've found projects to engage my mind. If I'm productive in my life, I am happy, and that transfers to my running.
"Before, I was a very serious Steph – always chatty, but so focused it was hard to switch off. So it's lovely to be part of a girls group – that's the beauty of Mick. He has such a scrumptious group, girls and boys. We are excited to spend time and train together. It's wonderful, so fingers crossed for 2014 in Glasgow."