While I was running I managed to put the following observations together and get to the right answer:
- Very long sequence of colours.
- Apparently random order of stripes.
- Four colours used.
- I was in Cambridge!
Of course, the big model of DNA at the end of the decorated section of cycle path didn't hurt (but I did work it out before I saw that - really!).
It is, apparently, a part of the human genome - a single gene which has a function in repairing other mutated genes.