What I noticed right away -- besides the fact that the song is very Euro early 80s Abba-esque -- is the fact that the chorus, where they sing "Leila Leila Leila" seems drawn from a hit by Saudi singer Mohammad Abdo's famous song "Aba'ad."
I got to know this song when I was doing fieldwork in the West Bank in 1984-85, it was much beloved by my friends, and I came to love it too. I thought the title was in fact "Leila," as that word is sung over and over in the song. And in fact many in the Arab world know the song by that name as well. If you're interested, here is a translation and transliteration of the lyrics.
In any case, check out Abdo doing a live version of the song. (And isn't it lovely? One of my favorite Arabic songs ever.)
The "leila" section of the song comes in at about 8:40. Yes, it's late in a very long song, but rest assured, this is a very well-known segment of the song.
Listen, then go back and listen to the Dolly Dots "Leila." Don't you think their chorus is taken from the Abdo original?
Now, the I didn't know this song while my friend Gamal did is that Dolly Dots are one of those European groups (Dutch in fact) who never had any hits in the US but were big throughout Europe and the Middle East. (A much more famous case is Boney M.) Dolly Dots were so popular in Egypt (where Gamal is from) that they even toured the country.
I posted my conjecture about the origin of the Dolly Dots' "Leila" chorus on Facebook, and my friend Robin shot back with this video. It's a re-formed Dolly Dots performing their '81 hit in 2007.
What is notable about this live version is that Dolly Dots are backed by a small Arab music ensemble (a takht), which serves to bring out more fully the Arab elements (and the Abdo influence) than did the original.
Neil contributed the fact that the ensemble is composed of Jamil Al Assadi, on qanun and Latif Al-Obaidi on oud, who belong to the Iraqi Maqam Ensemble, which regularly backs Iraqi singer Farida Mohammed Ali (based in The Netherlands), and the late Behsat Üvez from Turkey on derbuka. That is, it's a first-class ensemble.
(Shukran, Gamal, Robin and Neil!)
Added January 20, 2014: I meant to say last night that I think one reason that the Dolly Dots were never a hit in the US is: the name sounds ridiculous!