"Magna Carta was not really the product of `Bad King John' but a critical commentary on the whole of Angevin Kingship." Do you accept this comment or would you dismiss it as a "whitewash" of an evil and incompetent king.

English Historical Documents iii, ed. H. Rothwell translates the 1215 Charter in full and indicates in detail where the 1216 & 1217 reissues varied from it. Though there are many other translations, this one makes it easiest to see what contemporaries omitted or changed, hence to deduce why.

J.C. Holt, Magna Carta (1965; 2nd ed. 1992) has a full commentary; you can also take a look at Annotated Excerpts commented for naval cadets by my friend Richard Abels.

Holt's Magna Carta & Medieval Government contains various highly relevant essays including "The End of the Angevin Realm" & "King John", but not his "The Loss of Normandy & Royal Finance" from J. Gillingham & Holt (eds.), War & Government in the Middle Ages (1984) arguing for a financially stretched monarchy against Gillingham, who is much more inclined to blame John and whose own The Angevin Empire is readable & short! Gillingham also compares Henry and Richard in a way very favorable to Richard's reputation for constructive government in "Conquering Kings: Some 12th-century reflections on Henry II and Richard I", in T. Reuter (ed.), Warriors & Churchmen in the High Middle Ages: Essays presented to Karl Leyser (1992), cap. 10.

W.L. Warren, The Governance of Norman & Angevin England (1982) argues a different case; and his earlier, enjoyably readable, King John is lively with and especially good (cap. 1) on the chronicle sources for "Bad King John".
H.M. Thomas, Vassals, Heiresses, Crusaders & Thugs (1993) might cast light on the role of the "Northerners".

P.D.A. Harvey, "The English Inflation of 1180-1220", Past & Present 61 (1973) is the classic presentation of the case for a monetary inflation which would have had significant impact on John around Magna Carta.

M.T. Clanchy, From Memory to Written Record (2nd ed., 1993), esp. cap. 2 gives the evidence for the proliferation of writing in government and suggests to me that the years 1160/80 may have been the watershed for creeping legalism.