The copy here is analysed in H.J. Lawlor, ‘An unnoticed charter of Henry III, 1217’, English Historical Review, 22 (1907), pp.514-8.1 The preamble is that of the 1217 Charter but with the king acting on his free and spontaneous will. The end is as the 1225 Charter, so it includes the tax and has nothing about adulterine castles. The Charter is given by Richard Marsh on 6 November 1217. The text of Magna Carta is followed by a similarly hybrid version of the Forest Charter but, as mentioned above, without date and giving clause.
The cartulary is listed in C. Breay, J. Harrison and D. M. Smith, Medieval cartularies of Great Britain and Ireland (London, 2010), no.1373; ‘A Calendar of the Liber Niger and Liber Albus of Christ Church, Dublin’, ed. H.J. Lawlor, Proceedings of the Royal Irish Academy, 27 (1908-9), nos.58-59.