Not quite. The 10.5% is the pension levy. Some PS employments also pay 5% normal normal.pension contribution plus 1.5% spouses and childrens contribution. (aka widows and orphans, for those of a certain vintage!)
Pre 1994, modified (low) rates, usually Class B for Civil Service and Class D for wider public service.
Post 1994, standard Class A rates.
Pre 94s don't get state contributory OAP, post 94s do, but their pension is integrated so, effectively, the OAP is deducted from their occupation PS pension.
And finally, post 94 payscales are 5% higher than pre 94 ones - this was the deal done way back in the early nineties when the government agreed not to "go after" pensions paid to existing pre 94 civil servants. There endeth the history lesson for today.