It would be interesting to see what the pension is like for this position - you're giving up lifetime earnings for retirement earnings (and "serving your country").
UK civil service is a defined benefit scheme that each year from state pension age pays 1/42 of your average salary multiplied by the number of years you worked there. It's inflation linked. You also need to contribute several percent of your salary (various bands). The Government Actuarial Department modelling implies a cost to the employer of around 30% of basic salary.
