Having spent the first few months of my time in London drinking my savings away it was time to get real, get a job and find a real house. After paying rent and deposit my funds were seriously lacking and as such my diet changed from beer and curries to water and pasta, then I came across the winning combo.
Subway's sub of the day. Two quid for a 6" sub of the day, twice a day served its purpose. A different sub every day, and sometimes if I had the extra cash I'd splurge and get the foot long. Always had to make sure I got all the toppings so it was as big as possible.
This might be why I managed to avoid catching the "London bug" and blowing up in size whilst there.