An Anglican priest has finally cracked the code Methodist co-founder Charles Wesley used when writing about sensitive matters in his diary some 250 years ago.

Over 1,000 handwritten pages dating from 1736 to 1756 have been deciphered by the Rev Professor Kenneth Newport, pro vice-chancellor for research and academic development at Liverpool Hope University.

The transcribed pages reveal the extent of Charles' anger with his brother, fellow Methodist founder John Wesley, over the latter's plans to marry and disagreements over a split from the Church of England.

"He was very much opposed to separation, he saw the Methodist Societies as within the established church and anything that smacked of separation was something he took a very strong view of," Rev Prof Newport was quoted by The Telegraph as saying.

"At one point in the journal he is talking to the society at Grimsby and goes into block capitals and says 'I told them I would remain with them as long as they remained with the Church of England but should they ever turn their back on the Church they turn their back on me'."

In one section, Charles expressed his disapproval of John's plans to secretly marry Grace Murray because of her previous engagement to another man.

He wrote: "He (John) is insensible of both his own folly and danger, and of the divine goodness in so miraculously saving him."

Rev Newport has worked on the diary pages for nine years, studying photocopies of the originals which are stored at the John Rylands Library in Manchester.

His breakthrough in unlocking Wesley's code of shorthand and abbreviations came when he used the King James Bible to transcribe excerpts from the Gospels.

The transcribed diary pages will be published together with 9,000 never-before-seen poems and hymns.