definitely gross, 40+% to taxman!
Clearly someone who doesn't understand tax.
The figures are gross, but then all salary figures are as individuals have different allowances etc. The salary you will get post validation is roughly the same for each band, the difference between band 5 (top) and band 1 (bottom) is only around £3,000 initially.
For example, for a band 3 unit, your post validation salary will be just over £40,000 including the shift allowance. That is a gross amount. Take home pay for an average UK tax payer will be £2,500 a month (£30,000 per year net), less anything you pay into the very good company pension. That's an effective tax/NI combined rate of 25%, not 40%.
You remain on this amount after validation until you have been with the company for 3 years (from the start of your training). You then go onto the full ATCO pay scale, again at roughly the same point for all units. Again, for Band 3 this is around £56,000 per year gross. Again, take home will be around £3,300 per month net (£40,000 per year net) before any deductions such as pension etc.
You then get length of service rises each April until you reach top of the scale for your unit band. Band 5 rises much more quickly than Band 1, and quite a bit quicker than Band 3. If you do nothing else a Band 3 ATCO at the top of the scale currently will earn around £75,000 gross.
This annual rise is not cost of living, it is a pay increase. Cost of living rises are separate, where awarded, and negotiated generally by the union.