The England U21 international striker became Saints' record signing earlier this week.
â€śI had to think it over a lot,â€ť he told the Lancashire Telegraph. â€śI dreamed of winning promotion again and playing in the top flight with Burnley. That was my aim but it wasnâ€™t meant to be.
â€śIt will always be the first fixture I look out for â€“ especially when itâ€™s the derby games!
â€śIt will be a good season for them and I will try to get on as many games as I can.â€ť
He added: â€śIt has been hard for me to leave.
â€śThere werenâ€™t any tears, Iâ€™ve tried to keep it as professional as I can. It has been emotional for my mum and dad though. Theyâ€™ve said it will be weird seeing me without a claret and blue shirt on.â€ť