If you've gone to Allerton, you've gone too far.
Between the Aire bridge and the canal bridge, heading out of Castleford, the "Old Mill" pub is on the left which you have already located. Almost opposite, ie on the right, is "The Griffin" pub. Looking at the front of the Griffin, there's a narrow road to the left. That leads to Castleford 4x4 centre. Go down that road and stand looking at the 4x4 garage and the "Navigation" was on your left, backing onto the canal side.
David