What are the salaries like for a senior officer, assistant head or head position at one of the departments under PM office? I'm a little confused by the various career tracks such as administrative officer or the MX scheme.

I went for an interview this week for the position and HR called me to ask about my current and previous pay. Was a bit strange. I'm a phd holder, previous job (2.5 years) last drawn salary abt 6k, took a pay cut to explore a slightly different but related and more interesting job drawing salary of 5.5k ( only been here for 2 months). My education, and both work experiences are related to the position I applied for. Would HR factor in both my job salaries in calculating my pay?