Frenchay 2012 10k - short course wrong route followed?

Hi, would be interested to hear from anyone that did this one had took a wrong turn! Apparently the front of the field all took a detour which significantly shortened the course. I was browsing the results on line and nearly fell off my chair when I saw names of guys that I normally finish around in local races doing 3 or 4 minutes faster times. Panic set in and I thought they must have a year of incredible improvements! Then read about the above and was relieved. I wondered what time difference the detour accounted for. Thanks