While Somerville finally got his shot as a professional cricketer at age 30 with New South Wales, his success there was short-lived, with the presence of Australian test spinners Nathan Lyon and Steve O'Keefe leaving few opportunities, and causing him to look back to New Zealand for one last shot at fulfilling his dream.
Auckland came calling, and Somerville had a hope, but having played only two four-day and five one-day games since his return, an international call-up still seemed extremely premature.
So, when Black Caps selector Gavin Larsen called with the news he'd been hoping for his entire life, Somerville couldn't keep his emotions at bay.
"It means a hell of a lot - it's more than just a game of cricket in a way," he explained.
"I was incredibly emotional yesterday when I heard about it - my family's made a lot of sacrifices to come here with my children, it's been a long time coming. My dad's always told me that my career's a lesson in persistence.
"Having had my career outside of cricket as well, I know how privileged I am to be here, and I'm extremely grateful for the opportunity."
Despite not having played in New Zealand for a decade, Somerville says it was always a dream to represent his country of birth, and he never lost faith despite the long odds.
"I was always hopeful, always had a really strong belief. I dreamt of it as a little boy, I held on to that dream for a long time.
"I've been in and out of other jobs. I was a chartered accountant, for five years I worked and studied, and survived that somehow. As a spinner I think you get better with age, that's certainly the case with me."
He was helped by New Zealand's lack of spin depth. Astle and Mitchell Santner are injured, and with selectors looking for a right-arm off-spinner to complement Ish Sodhi and Ajaz Patel, there were literally no other realistic options.
Still, Somerville admits he was shocked when he got the call from Larsen on Thursday morning.
"I thought [the call] might have been about the [New Zealand] A games coming up against India, I was hopeful to play in those.
"I was very shocked - I was like 'What's going on?' but I couldn't be happier - I'm over the moon.
"The plan was to come to Auckland and play three to five seasons and see where it took me - obviously it's come a bit faster than I was expecting."
Whether Somerville will play against Pakistan will likely depend on pitch conditions and how many spinners are plumped for - he could get the nod over Patel - but Somerville believes he will bring a different element to the team.
"I've got a lot of variations with my off-spin bowling, I'm not just bowling the same ball all of the time.
"I bring some positive energy and I'm a laid-back character - I like to think I stay pretty calm.
"I have fun and keep a smile on my face as well."
It's a smile that will be hard to remove, as Somerville finally realises his lifelong dream.
