Just send a Direct Message to @AlderandAlder on Twitter, or email jonathan@alderandalder.co.uk - first reply with the right answer wins... Come on, what are you waiting for!
This is important: Don't tweet the answer in the open - so everyone can see it - because you will be disqualified: We won't be able to include any entries received after that in the 'grand prize'. You can find out more about the Alder and Alder Advent Quiz here.
The answer to yesterday's letter
An easy one to start: McDonalds
