While listening to "The Island Years", I was surprised to find that the first track is slightly reaggae-ish, and a bit different from their music.

Maybe someone can tell me something more about it? Was it written in the wake of bands like Police? Just wondering....

do you mean "young savage"? (i don't have the island years comp). i always thought it's sounds more punk-y than reggae-ish.

The is quite a distinct reggae influence in the early Ultravox material. Island studios were full of reggae artists, and the band were recording at the same time as Bob Marley and Lee 'Scratch' Perry, who introduced a lot of techniques and ideas to John and the others.
Chris Cross brought this to the Ultravox sound I think, influenced by the dub sound from the streets and clubs in Tottenham - check 'Dangerous Rhythm' for example.
You can still hear elements of this in Underpass especially, which has a 'dub' bassline - carried over from the earliest versions of Touch and Go an He's a Liquid which (when performed by Ultravox in 1979) started with a lot of reggae-based guitar sounds.

Hope this helps.

I hadn't noticed it in Young Savage though - so thanks for a great excuse to listen to that again.

No, it's Dangerous Rhythm. Yes, very pleasant and radio-friendly reggae sound.
Don't quite know where it came from musically.

I've always thought of that track as being heavily influenced by Roxy Music, not least for the vocal delivery.