Some interpretations, starting in the Victorian era, place the Lancastrians with the River Nene at their back and state that they had dug entrenchments and gun emplacements facing southwards and uphill. In fact several contemporary accounts indicate that the camp was in an existing park on the south side of Delapre Abbey, or at least in the open fields of Hardingstone which lay between the Abbey, the village of Hardingstone and the Queen Eleanor Cross. It also seems that it may have been an existing park pale that was used by the Lancsatrian forces as a defence. Based on the sources the camp could have been oriented either North/South, in an area now known as “The Rookery”, making use of a water course known as the Fulbrook to provide a moat or ditch for the defences, or East/West on the modern golf course.
The advance guards of the two armies clashed, probably at St Leonard’s bridge, now culverted over. This saw the Lancastrian contingent under “Lord Greriffin” routed by the Yorkists under John, Lord Scrope of Bolton. In the pursuit the Yorkists entered Northampton where much damage was done.
The Yorkist main army deployed either to the south of the Lancastrian fortification, along the top of Hardingstone Hill, or to the west, along the line of the modern A508 road, and, possibly in pouring rain, advanced towards the enemy in the valley bottom.
The battle was over in remarkably short time, perhaps only half an hour. The Lancastrians were hampered by the rain either on the day or from the day before flooding their gun positions. This, or some other, unknown, reason made their artillery ineffective. However, the ditch and the fortifications still made a considerable obstacle, until Sir Edmund Grey changed allegiance to the Yorkist side during the course of the battle and his men helped the attackers into the camp. After this intervention the battle was over swiftly. The King was captured and many of the Lancastrian nobles were killed, including the Duke of Buckingham, the Earl of Shrewsbury, Viscount Beaumont and Sir Thomas Percy, Lord Egremont. Many of the common soldiers seem to have drowned in the rout as they fled the battle across the River Nene.at Sandiforde Mill.