On an income of £130,000 with a pension contribution of 3% your take-home is £76,596 under current tax levels. Which is an effective tax rate of 41.8% including NI. Using the same metrics with a pre-tax income of £120,000 the take-home is £72,699, a contribution of 39.4%.
So that 40% mark falls somewhere between £120,000 and £130,000. The average pension contribution is between 2-3%, so I went with 3. Although I think this has increased to 4% recently.
I haven't included VAT or council tax etc. as they're independent of your earnings and Terminal Boy hadn't mentioned them.