I've finally relented, and the series is now available on Google:
Zombies vs The Living Dead
Book 1: London
Book 2: Wasteland
Book 3: Family
Book 4: Unsafe Haven
Book 5 - Well, probably next week.
I was reluctant to do this up until now due to Google's pricing policy – they will occasionally make a book free without asking an authors permission. Doing this would have messed up my marketing plan. Since I decided to ceremonially burn my marketing plan on Tuesday (I dressed up in robes) I figured, why not put it on Google?
Some things to note - due to this odd discounting policy you may find books on Google Play cheaper than Amazon by as much as 30% or so. Usually Amazon will match the price – they have 'a never knowingly under sold' policy, but that can sometimes take a few days, so if the budget is tight, they might be worth a browse.