Great answer Flt Lt The Lord Flasheart; if you had told them about your time on the VC-10, L-1011 and the C-17 they would have been incandescent with rage.
At least by telling the world that you were on the Hawk and the Harrier you have removed all doubts that your experience is far in excess of anything that BA could possibly produce.
You should certainly expect at least 15 years of notional seniority in BA. Good luck; I only got 10 years notional seniority when I left and joined civil aviation.
Let's face it, it is money for old rope. I can't remember when I was last required to exceed 30° of bank. Most of the lesser mortals that I have to fly with would have no idea how to recover from a spin on limited panel.
Come to think of it, most of them have never actually had to do a spin!