Could I eat for £1 per day?

Mumma Troll has set a challenge: To feed a family for £1 per person per day for a week. I'm all for spending as little as possible on food (and everything else) and was about to sign up for this, but Ian stopped me. He thinks this is unrealistic and since he's the family in question, I suppose he has a right to say no.

This got me thinking - is it really that unrealistic? I'm pretty tight with the budget as it is, so what do we spend on food at the moment, on a cheap day?

Breakfast

Cereal, usually oats.
Oats, 75g : 7p (that took ages to find because I couldn't remember how big the bag was! Also, it turns out my 'portion size' is rather large ;-) )
Milk, 300ml : 19p
I'd usually have hazelnuts, raisins and half an apple with this, but to save money (and the faff of costing them) I'll just have sugar
Brown sugar, 10g (if I'm honest) : 2p

Breakfast total = 28p

Lunch

A couple of slices of bread and butter. I'll skip the marmalade today because costing homemade marmalade is too much like hard work!
Homemade white bread, 1/5 loaf : 4p (brown would be 10p) [edited - I counted the yeast for the whole loaf before]
Butter : 5p? (That's a guess. I don't really know how much butter I spread on my bread.)

Lunch total = 9p

Dinner

Pasta with tomato and bacon sauce.
Value pasta, 50g : 3p
Cooking fat rendered from saved bacon fat - I can't cost this!
Half a small onion : 7p
Half clove garlic : 3p (that would be cheaper if I hadn't bought organic)
Half tin value tomatoes : 17p
One and a half rashers bacon : 19p
Sprinkle of mixed herbs - too difficult to cost. Same goes for salt and pepper.
Squidge of lemon juice : 2p

Dinner total = 51p

Drinks

Three cups of tea and one glass of cheap squash. I'll skip the 'fresh' juice today, to save money.
Three teabags : 20p (would be cheaper if I didn't buy fairtrade tea)
120ml milk : 7p
Squash, 40ml : 2p

Drinks total = 29p

Total for the day = £1.17

This isn't hugely over the £1 budget. If I cut the bacon from the pasta sauce (making it unacceptable to Ian) I'd be just under the pound, or if I drank only tap water all day, I'd be easily under budget. It's interesting to note what I've already cut, though. I chose white bread instead of brown because value flour is only available in white, and the same goes for pasta and rice. I cut the fruit and nuts from my breakfast and skipped the fruit juice. This is a fairly stodgy meal plan - I certainly don't have five portions of fruit and veg in it. It seems that refined carbs are a relatively cheap way of eating.

This little exercise has shown me that I could survive on £1 a day for food if I had to, which is nice to know. I don't fancy doing this for the whole week's challenge though (even if Ian would let me) and I'm not sure I'd even want to do it for a day. No tea? That is hardship indeed!