The cheeky smile on Maurice 'Mo' Johnston's face when he signed for Rangers made it clear he knew exactly what he was doing. Celtic fans were furious when Johnston let the ink dry on a Gers deal, because he had previously outed himself as a lifelong fan of the Parkhead club. Playing with Celtic from 1984-1987, Johnston had moved to France with Nantes. By 1989, the little ginger was back in Scotland, only this time he was plying his trade at Ibrox. Playing 76 games and scoring 31 goals for Rangers, Mo Johnston became a favourite for his playing style, but there was still a portion of the Ibrox support which didn't welcome him. On the other side of the city, Celtic fans hated Johnston for making the switch. Having been a staunch Celtic supporter before linking up with Graeme Souness at Rangers, flames were fanned by the fact that Celtic had been interested in taking the player back from Nantes. Out of nowhere, he was a Teddy Bear, in one of the most dramatic transfers in Rangers history. Maurice Johnston grew up a fan of his new employer's rivals, so it's plausible that he regrets the decision to effectively turn his back on his boyhood club. What other players do you think must regret signing for Glasgow Rangers? Do you agree with the choices listed here? Let your voice be heard down in the comments section below!