The Tiltyard causeway dammed several small streams, most notably the Finham Brook and the Inchford Brook (previously known as Tunckses Brook), creating the shallow lake, or mere, covering an area of 111 acres as part of the castle defences.   The mere was well stocked with fish, providing an additional source to the elaborate set of fishponds South East of the Brays.

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         The turret midway along the west wall contained a sluice which could drain the mere, described in a survey of 1545 and by Dugdale as ‘strong hedys of stone with slewssys’.   As late as 1821, it was recorded, that this ‘stonework … in part remains’, but any such remains were swept away by a deluge in August 1834.

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         Historian M. W. Thompson, writing in 1965, determined that the dam was originally only 8 feet high, but was raised by a further 12 feet circa 1200, by King John, to support a higher level of the mere of 262.5 feet (or 80 metres) above sea level.

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         John Dudley enclosed the dam with walls either side, and the area became known for its jousting events.      Previously, in the 15th century, jousting was more likely to have been in the North court, now the garden, or even within the Brays.   Robert Dudley drained parts of the lower pool to the East to create terraced walks and an orchard, to which the small gate outside Mortimer’s Tower provided access.   He may also have widened the Tiltyard at this time, using stone from the outer ward chapel.

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         On the 9th day of the 1575 royal visit, the bridegroom of the mock wedding made the first and successful tilt at the Quintain, a customary entertainment at such events.   ‘Running at the Quintain’ came from martial training, whereby a mounted lancer would practise striking down at the chest of an opponent.   A sack tied to the opposite end of the Quintain crossbar was for ballast and could not unseat the rider as typically described.