One Week to go - New Boots

I can't quite believe it, but with just one week to go before starting an 1100 mile walk, I'm buying new boots!  I know that this is a classic mistake that could end up with nasty blisters on the first day, but I don't really have any alternative.  I had planned to set off in a pair of Salamon Quest 4D GTX boots that I bought last summer and have spent the best part of a year breaking in and until now feeling very comfortable with.  However, in the last week during my daily 20K walks to and from work, I have inexplicably started feeling my toes touching the end of the boot.  I can only think that my feet have expanded with the extra walking.  Either that, or the boots have somehow shrunk.  Either way, this it is a problem that can only be resolved by buying new boots.  I have decided to get the same model again, half a size bigger and to see if I can break them in in the 7 remaining days.  If not, then I'm going to be in for an especially painful first week or two of this trip!