Almost 65% of Prospect members voted in the ballot which opened three weeks ago. Close to 80% – a ratio of 4:1 – of members rejected the offer.

The offer to staff working across the MoJ was for five years. They were offered 3% for the first three years followed by 1% in the fourth and fifth year.

However, working hours would increase to 38 hours a week from a mix of 35 to 37 hours.

The offer, which was above Treasury guidance, relied on a business case made by the MOJ that any pay rise would be at no extra cost and would be paid for out of existing staffing budgets.

This rationale resulted in proposals to change a broad set of terms and conditions including: increasing working hours, reducing allowances and reducing paid overtime to a flat single time rate.

The MoJ also proposed reducing travel and subsistence rates, which would have cut the overnight allowance from £23 to £9 and reducing mileage rates from 35p to 25p a mile.

Other changes included scrapping the London allowance and replacing it with a non-consolidated, non-pensionable payment of £500 in the third year of the deal, followed by £1,000 in years four and five.

Occupational sick pay was also in line to be reduced to a maximum of five months full pay and five months half pay for all staff. The current terms for many staff are a maximum of six months full pay and six months half pay.

The proposals also included regrading the top pay band by splitting it in two and going back to the standard civil service grading classification. This caused huge uncertainty for this group of staff.

Prospect negotiator Brian Harris said: “During the negotiations, Prospect raised a number of concerns about the length of the five-year deal, the allowances that were being removed, flat rate overtime and other significant changes to staff contracts.

“Our members have overwhelmingly voted to reject this offer as the uncertainty and price of changes to terms and conditions were too severe. We will be going back to the MoJ to discuss the next steps after our members made such a clear decision to reject the offer.”