The fly-half, who only turned 20 at the end of March, has accepted a two-year academy contract at Championship leaders Bristol.
Searle agreed the deal earlier this year, but it has only now been officially confirmed after Albion’s National One title hopes were ended at the weekend with a heavy defeat at Ampthill.
The Cornwall player said it was not an easy decision to leave Brickfields.
“It was a tough decision,” he said. “But it was one of those opportunities that I felt I couldn’t turn down as I might regret it later.
“I will miss it at Albion, but I have to put rugby first.
“However, I am really grateful for what Albion have done for me. They have given me a good opportunity and since I’ve got into the team it has gone really well for me.”
He added: “Without the opportunity Graham (Dawe) has given me I would not be in this position, so I am really grateful.”
Searle insists his move to Bristol is in no way connected to Albion’s recent announcement that they intend to go into administration to sell the club.
“It is nothing to do with the situation at the club,” said Searle, who trained with Bristol in early March.
The former Okehampton junior does say his mind is totally on Albion at the moment.
“I want to help Albion finish as high as they can,” he said. “I will keep playing as hard as I can for them. It is not going to affect me for the rest of the season. Hopefully, we can get four big wins.”
Plymouth’s faint hopes of chasing down leaders Richmond ended with a shock 52-13 defeat at Ampthill on Saturday. It was club’s first away defeat since November and their first of any kind in three months.
“It was very disappointing on Saturday, especially after the good run we had been on,” said Searle. “I don’t think anyone turned up really. It was just one of those days you want to forget about and move on. We just have to focus on next week now.”
Searle could have stayed for a second season at Albion and been a regular starter, but he has opted to move to a club where he could be fifth choice.
Last week, the Premiership promotion hopefuls announced the signing of Samoan international Tusi Pisi. They already have Gavin Henson, Adrian Jarvis and youngster Callum Sheedy, who can play at 10. Sheedy has been dual-registered with Albion’s National One rivals Cinderford.
“It will be tough to get in the team, but I am going there to develop my game in a full-time environment,” said Searle. “Hopefully, I learn from the more experienced players at Bristol and can push myself into the team, that’s what I’m hoping for, but if I don’t it is just one of those things.”
As Searle is joining Bristol on an academy deal he could be dual-registered with a lower league club.
Albion’s director of rugby Graham Dawe refused to rule out seeing Searle back at Brickfields in the future.
Dawe is hopeful Plymouth can keep the majority of their young and talented squad, providing the club’s future is sorted out within the next few days, but he acknowledges that playing in the third tier of English rugby means there is always a chance a few players will move on to higher league clubs.
Searle joined Albion from Launceston, who themselves were in a lower league.
“In the division we are in there is always the potential to lose players to higher level clubs,” said Dawe. “That is part and parcel of being a National One side, but equally we can attract other players who want to play at this level.”
He added: “We wish Billy well in his quest to play at the highest level he can and he goes with our blessing.
“He has been a really good player for us and, because of his age and ability, Bristol have seen his potential.”
Albion’s coaching staff felt Searle and team-mate Ollie Dawe deserved a call-up to the England Under-20 squad, but they missed out with only academy players getting selected.
However, not many players Searle’s age have played nearly 50 National League games and featured in a senior Twickenham cup final.
“Billy took a different route to a lot of young players,” said Dawe. “But he is now one of the best fly-halves, if not the best, in the country in his age group.”
Bristol are also believed to have looked at some of Albion’s other young players, with Dawe’s reputation for spotting talent well-known in rugby circles. During the mid-2000s they made a habit of signing Plymouth’s best players with Dan Ward-Smith, Luke and Tom Arscott, Lee Robinson, Ed Barnes and Alfie Tooala all heading up the M5.