Well, I can give you a much quicker answer this time, jigjag - because (p)ETER and (k)EVIN are not proper words until they've got their heads on [you got lucky with (d)AVID, though).
I'm sorry, brendan - highlighting words that aren't even the subjects of the sentences containing them tends to place a false emphasis on them.
Normally, I'm more guilty than most solvers when it comes to looking for extra depth in a puzzle, but in this case Ifor's beautiful puzzle would be marred by it (in my opinion). The 'everyman' nature of 'If' is adhered to scrupulously here.