Harrison, 34 — caged for a vicious assault — bulked up during his 2½ years behind bars in a nick on the Costa del Sol before being released yesterday.

 

And the ex-WBO title holder was so determined to return to his past glory he began sparring with dad Peter, 62, in the garden of his apartment within hours of being freed.

Harrison also showed off his super-fit physique as he strolled with fiancée Stacey Gardner, 27, and toddler Jack in the resort of Estepona.

And the star, who has battled a booze problem, vowed: "I will be World Champ again. Nobody's going to stop me. One thousand per cent.

"What keeps me going is my children and my family. I'm going to be the champ again for them."

He also told a pal just before being released from the maximum security Botafuego nick that he had ditched drinking for good.

He said every day of his horror ordeal inside the Spanish prison system had been "hell" — and admitted he had caused his own downfall.

He added: "I promise I will never go back to the way I was. I don't know who that person was — but it wasn't me. This is me now, and I am going to be back on top."

 

Tasting freedom ... the boxer leaves prison with belongings on Saturday and at Gibraltar airport yesterday

 

The troubled ace, from Glasgow's Gorbals area, walked out of the notorious jail three miles from coastal town Algeciras