How much lunch money do you give dc?

[Contessa101]

I was just wondering how much lunch money I will need to give dc when at Secondary school next year. I know planning ahead a little, but I just have no idea of what is a reasonable amount.
Just wanted to know how much other children receive and if packed lunches are common?

Mine get £20 each at the start of the month, and this will buy them 8-10 school meals. Then they take packed lunches for the rest.
It's intersting watching them work out which days they need/want sandwiches depending on their lunchtime activities.
My reasoning is that they will be off to Uni soon enough and the money they will have to live on then will not cover a bought lunch each day.

Are packed lunches socially naff, then?

Most kids at my DS's high school seem to do packed lunches in the main, with one or 2 days of lunch money to spend on chips fruit and muesli