Seven men A, B, C, D, E, F and G are standing in a queue, one behind the other in that order. That is, A is first in the queue while G brings up the rear. Each of them is wearing a hat of a different colour of the rainbow – Violet, Indigo, Blue, Green, Yellow, Orange and Red – but not necessarily in that order. It is also known that: • D can see in front of him green and blue hats, but not the violet hat. • E can see violet and yellow hats, but not the red hat. • G can see hats of all the colours except Orange. • E is wearing the Indigo coloured hat. What colour hat is worn by F?