I agree 100% with Sarenco unless the individual has fairly serious known health issues.
That said, if you want to be methodical about it, model it on a spreadsheet, year by year. Look at the person's specific tax position. Take the net (after taxation) yearly annuity payment, include indexation if relevant and see how long it takes for the net annuity payments to exceed €30,000 in total. My guess is not very long.
I'm not familiar with the Tesco DB pension scheme, so you should also ask for a copy of the latest statement showing what sort of financial shape it's in.