Last season was Murphy's first as a senior - she only turned 20 last September - and her victory in Birmingham qualified her for an appearance at the World Championships, where she ran against the likes of Merlene Ottey and Irina Privalova in the relay.
At last Saturday's match against Russia she lowered her indoor personal best to 23.46sec, a Welsh record, and close to her outdoor best of 23.40; the Olympic qualifying mark of 23.24 looks fully within her capabilities.
These are exciting times for Murphy. Exciting, and exhausting. She is currently at full stretch in her efforts to combine athletics, for which she trains five nights a week, with serious studying: she is half-way through a three-year law degree at Brunel University.
Having dealt with criminal and family law, she has had the luxury of a week's break before this weekend's competition. Then it is back to university to acquaint herself fully with court procedure, rules of property and US constitutional law.
"By the time I have studied in the day and trained at night, there isn't room for much else," she said. Sleeping, not surprisingly, has become a favoured pastime.
Murphy, however, has already demonstrated her staying power. Her last AAA indoor sprint title was won six years ago, and in the intervening time she encountered a run of injuries - to hamstring, knee and ankle - which virtually wiped out two seasons. Female athletes aged 15 or 16 are notoriously prone to dropping out of the sport, but Murphy has hung in there.
"I always knew that I was capable of beating the people who were winning while I was injured," she said. "Although I didn't expect to go as high as this when I was older; I used to think I was only winning my races because I was so tall for my age."
Murphy's career began to revive two years ago, when she joined Mike McFarlane's training group at Haringey. John Regis, Tony Jarrett and, more recently, the Commonwealth Games finalist Geraldine McLeod have all helped with advice and support. Richard Simmons, the national sprint coach, sees the strength of McFarlane's group as one of the major reasons for her success in the past 18 months.
"She is also reaping the benefits now for a strength training programme she started on two years ago," Simmons said. "That is a very important factor for women, but for many of them it is quite a step to go into a weights room and take on that kind of work.
"She still needs to work on her speed base; her times for 60 and 100 metres are not that good. But in the long-term she has got outstanding potential in the 400 metres, which could turn out to be her best event.
"Catherine is a big talent. She has made a lot of progress in the last 12 months, and it shows no sign of stopping. She hasn't done a lot of preparation for an indoor season but she is going well already."
Murphy has also received enormous support from her parents, Judy and Eamon, who were both athletes of note themselves. Her mother was Welsh 100 yards champion at 14; her father was the Staffordshire county long jump champion.
Not surprisingly, the Murphy household - in Hemel Hempstead - has always followed athletics with interest. "I remember sitting watching the 1984 Olympics," she said. "My parents couldn't get me away from the television." Twelve years on she could be even more closely involved in the Games.
Murphy's re-emergence in the past two years has been welcomed by Keith Antoine, who coaches her main rival, the 21-year-old Katharine Merry. "Catherine has made a good step up from the junior ranks," Antoine said. "It all adds to the competition. The next generation are coming along and saying: 'We intend to take over.' That has got to be good for the event in this country."
Merry is still recovering from an operation she had after Christmas on her calf, but she is back in training and looking forward to challenging for an Olympic place. With Paula Thomas in decent form after a recent training break in South Africa, Britain could have three women 200m runners in a major championships for the first time in several years.
That is the sort of base from which it is possible to strike out towards individual international medals... but for now, Murphy is simply concentrating on stepping into the Olympic arena. Another title in Birmingham on Sunday will keep her moving in the right direction. At 5ft 8in - tall, but not outstandingly so - she is finally being persuaded that her success is down to more than her height.Reuse content