The Blades defender signed in December 2004 but has spent the last remaining three months at Watford following a fall out with Neil Warnock.
DANNY CULLIP
It has been suggested that Highfield Road boss Micky Adams may temp Warnock to sell by offering striker Stern John who has been a suggested target as part of the deal.
This offer could put the Sky Blues in the driving seat as Hull City are also suggested to be linked with the un-transfer listed centre-half.