Unfortunately, he was sent Home with his tail between his legs, as the attempt at initiating an instant impact fell distinctly flat.
On Sunday evening, the five new faces on Pompey’s six-day tour to Dublin – plus youngster Joe Hancott – were instructed to sing in front of their team-mates.
It’s a ritual which has become commonplace in football, stretching through eras and rolled out in clubs of the football variant across the length of the country.
Harrison, the summer recruit from Ipswich and an amiable addition to the Pompey camp, opted for a rendition of John Denver’s 1971 song ‘Take Me Home, Country Roads’.
A popular tune among Manchester United and at beer festivals, he thought he was onto a sure-fire winner among his team-mates.
Not so, it seemed.
He said: ‘I thought it would get people involved, but I was on my own when I sang it! I was left out to dry.
‘That’s a song that gets everyone dancing and singing, but on this occasion didn’t. It backfired right into my face.’
Meanwhile, it remains the unanswered question of the summer – just where is Nathan Thompson?
The combative right-back has set the bar high at Fratton Park for pretenders James Bolton and Anton Walkes to reach.
His desire to test himself at Championship level prompted the rejection of a new Pompey contract and cutting ties with his home of two years.
A step into the unknown it seems – for even his former team-mates remain in the dark over his current whereabouts.
Despite remaining in the players’ WhatsApp group, nobody is any the wiser over Thompson’s footballing destination.
It seems Kenny Jackett’s squad – as well as the supporters – are confused over the 28-year-old’s next move.
Presumably he had somewhere lined-up to prompt turning down the opportunity to remain at Fratton Park. Presumably.
So where is he? We are all watching with much interest.