The Church of England is facing a “major constitutional crisis” following the defeat of legislation to introduce the first women bishops, according to an internal document written by one of its most senior staff.

Steps must be taken by July next year to consecrate women bishops and vote them through by 2015, or it risks the matter being taken out of its hands by Parliament, a memo by William Fittall, secretary general to the General Synod, said.

The document, leaked to The Times, is addressed to members of the Archbishops’ Council, a group made up of the archbishops of Canterbury and York and other leading clergy and lay people in the Church of England.

The Times reported that Mr Fittall, the Church of England’s most senior “civil servant”, wrote the memo within 72 hours of the vote last Tuesday which saw the legislation carried in the General Synod houses of bishops and clergy but fail by six votes to achieve the necessary two-thirds majority in the house of laity.

The decision has badly damaged the Church of England, Mr Fittall wrote, describing a “sense of shock”.

“Within the Church the effect on morale – particularly but not exclusively on that of female clergy – is severe,” he said.

Mr Fittall reportedly outlines a plan that would lead to simpler legislation, such as a clause to consecrate women bishops with no provision for opponents, being put to the General Synod when it meets at the University of York in July.

After going through revision committees and the dioceses, it could be ready to vote through to Parliament by 2015 or earlier, he said. “We have to do so because time is not on our side. Parliament is impatient,” he said. He also warned that unless the Church of England could prove very quickly that it was capable of dealing with the problem, it would be into a “major constitutional crisis” in Church-state relations.

The Archbishops’ Council will debate the issue this week before a meeting of the Church of England house of bishops takes place next month.

The defeat of the legislation to introduce women bishops came in spite of more than seven in 10 synod members voting in favour of approval. The legislation has also been backed by 42 out of the 44 Church of England dioceses.

Culture Secretary and minister for equalities Maria Miller told the Guardian newspaper at the weekend that it was “extraordinary” and “very disappointing” that the vote had failed, and urged the Church of England to examine its “procedures and processes”.

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