The Marathon world-record holder could only manage a third-place finish on her return to competitive action following an 18 month break as she finished behind Jo Pavey and Gemma Steel in the capital.
Afterwards, the 37-year-old admitted to being disappointed with her performance but revealed she struggled with a back injury throughout the run.
"I've got a tear in one of the discs in my back which has meant I can't go on the track, but I thought I was going to be fine on the road," she said on BBC Radio Five Live afterwards.
"It's sciatic pain and I just lose power in my legs.
"I've beginning getting treatment on it and I thought I'd be okay. It wasn't particular sore in the race, it just felt like I didn't have any power out there."
Radcliffe is hoping to enjoy glory at the London Olympics next summer but admits she will need to improve ahead of next year's event.
She added: "I hoping this isn't a big setback ahead of the 2012 Olympics."