Quinn has hardly featured in Sir Bobby’s first-team plans in the past 18 months, but has been in impressive form for the Blades during his four-week loan stay.
Neil Warnock was initially keen to extend the loan by another month, but now looks set to agree a £600,000 fee for the full back.
Newcastle director of football Gordon Milne was at Bramall Lane on Saturday to watch the Blades 4-3 FA Cup win over Ipswich, prompting speculation that he was checking on the form of Town winger Darren Ambrose.
A more likely explanation is that he was there to complete negotiations for Quinn’s move.