And there is no question whose side she was on.
Wearing a powder blue India one-day international shirt, the 20-year-old was cheering for the visitors in the first Test between India and England, even though she was born and raised in Britain.
"You're Indian if you come from India, and your roots are in India, so why not support them?" she asked rhetorically.
"That's who you are - you're Indian."
Purohit was one of several fans at Lord's, and indeed around the country, with conflicting identities illuminated by the India-England series.
More than a million Britons identified themselves as of Indian ethnicity at the last census six years ago. That equates to nearly two per cent of the country's total population and the proportion jumps to six per cent in London.
So it is little wonder that England cricketers are noticing the conflicting loyalties.
"I'd like to think British people would support the English team but I understand there's a lot of heritage there for a lot of English Asians and that goes back a long way," England opener Andrew Strauss said.
"They are free to make their own choices, no problems from our point of view. Hopefully, we can drag them round to our side in the future at some point."
British Indians are the largest ethnic minority community in London, and in Britain as a whole, and when factoring in people who identify themselves as of other South Asian ethnicities, there are some 2.3 million British Asians, or four per cent of the population.
Bhavic Amin, who identifies himself as an Indian, before explaining he was born and grew up in Britain, sides with Purohit when it comes to his cricketing allegiance.
"When England plays other countries, I support England, but when it's England-India, I support India," the 20-year-old said.
"You've got to know where your roots are, basically, don't you?"
In Amin's view, parental influences play a key role.
"It's a personal choice. It's how you're brought up. Some parents want their kids to be British, some want them to be Indian."
Conservative former cabinet minister Norman Tebbit highlighted those conflicts nearly 20 years ago when he controversially formed what has been dubbed the "Tebbit test".
According to him, one way to judge whether an immigrant was fully integrated into British society was to see which side they supported at cricket.
That view was not universally shared at Lord's, though, with Kal Patel, born and raised in Britain and a self-confessed England supporter when it comes to football, admitting that in a crunch situation in cricket, "I'm a true Indian supporter.
"Every person, whether you're Indian, Pakistani or Bangladeshi, if your home team from back home visits, even if you've never visited before, it's still your heritage," the 30-year-old said.