Actually corrected it for you before someone jumps on you. The GPP is a different award.
Wiki:
In 2013, Corbyn was awarded the Gandhi International Peace Award for his "consistent efforts over a 30-year parliamentary career to uphold the Gandhian values of social justice and...
For a bit of balance, here's the next page of that book.
Both pages conclude maybe his talking to Sinn Fein didn't directly help the future peace talks, but it didn't do any harm either. He just didn't hide it.