- The challenge starts 1st January 2012 and muct be completed by 12th December 2012.
- The orchestra must be a minimum of 30 musicians in size, and a maximum of 100.
- Shaun has to meet the musicians for the first time on the London Underground (and must be actively within the boundaries of the Underground station).
- The musician Shaun meets must be carrying their instrument (or part of it) when he meets them for the first time.
- Shaun must not know the musicians personally nor have met them or have communicated with them before. (i.e they must be complete strangers to him).
- Shaun is, however, allowed to pick musicians he currently works with, but they will not be included in the total orchestra count.
- The venue to be played at has to be from a list of 12 top venues agreed prior to the challenge.
- Shaun must compose all the original music himself (he still cannot read a note of music).
- If Shaun sees a musician on the London Underground, he HAS to speak to them.
- Shaun must contact each musician personally to recruit them. He cannot use mass mailouts, and must have personal one-to-one confirmation from the musician that they have signed up.
- Shaun must not include buskers performing within the London Underground, only musicians travelling as passengers. He is, however, allowed to recruit a busker who is travelling to and from their pitch.
- Shaun will ask the musicians he meets if they are interested in the challenge and will only provide further details to a musician that says "yes" or "maybe". If the musician says "no", he cannot continue explaining the challenge.
