Labour introduced the pension restrictions for higher earners in 2006. The annual allowance (AA) was set at £215,000 and the lifetime allowance (LTA) at £1.5m (according to CPI inflation these would be £340,000 and £2.37m by now).
They tended to increase annually and when George Osborn started cutting these allowances in 2011/2012, AA had reached £255,000 and LTA £1.8m.
The current levels are AA £40,000 and LTA £1.0731m and the budget will increase the AA to £60,000 and abolish the LTA.
In 2016 the conservatives introduced the Tapered Annual Allowance (TAA). By now this means that for those earning salaries over £240,000 only annual pension contributions of £4000 are tax free. The budget will increase this to £10,000 for salaries over £260,000. These TAA rules largely make the LTA irrelevant, which is why it can be abolished, and it is these TAA rules which mean the very high earners will not benefit massively from the budget changes.
As a few previous posters have pointed out, these pension rules have badly affected experienced NHS consultants and GPs due to the good pension schemes to which they belong. They have resulted in many retiring early or working part time as their pension hits the punitive limits. If you want an example consider this:
Consider a Senior Doctor aged 58 earning £120,000 who has built up a pension that will pay a lump sum of £150,000 and a pension of £60,000 if they retire now (and all these figures will increase significantly if they continue to work until 66). The pension rules apply to defined contribution schemes, and for a defined benefit scheme like the doctor's the equivalent amount is calculated as lump sum + 20 x pension, so in this case 150,000+20x£60,000 = 1,350,000. This is over the current LTA so the doctor faces a tax charge of 25% on £381,000 (1350000-10731000) ie. a tax charge of £95,250. This charge reduces the doctor's pension by 95250/20 = £4762.50/year so the doctor will receive £55,237.50/year instead of the £60,000 to which they are entitled. If they continue working the deduction will increase every year. Is it any wonder doctors in their fifties and sixties are retiring early or going part time?
Surely it is better for society if this doctor with valuable experience continues to treat us (whilst also paying over £45,000 income tax and NI each year).