From the Huffington Post:
"He opened his rucksack and had a gas mask and spray paints inside. He got out a piece of paper and had colors marked on it of what he had been trying out, and he dropped his colors," Ben told England's North West Evening Mail.
"I picked them up for him and after that he started signing it in weird letters and numbers," Ben continued. "He said, 'Do you know who Robin Banks is?' I said, 'No,' and he said, 'This will be worth about £20,000 -– have a good life, brother.'"