Can't remember sci fi book title or author

[Tones12345]

Hi, hoping you guys can help. I read this book somewhere between 95-05 and am guessing it was written in the 80s. It's sci fi set in the distant future. Humanity is doing well in the stars having won their war with a telepathic alien race that almost destroyed them. The main character has some role (can't remember how much) in the victory. He was captured by the aliens when young so he knows their language and culture. He also has some of their mind powers. He spends most of the book being chased across a world/worlds, before being captured in a spaceship by soldiers wearing telepathy immune helmets. It's explained that the helmets were developed late in the war and never used due to the war ending early which is why no one knows about them. The aliens might be white/grey and tall/lanky. MC is military ish and definitely has at least one scene in a mansion on a hill and a motorbike. Possibly purple in the cover. Please help!