Cineworld Showing Inbetweeners With Ads But No Trailers

Went to see Inbetweeners 2 at local Cineworld on Thursday evening. Normally you get adverts followed by trailers which can go on for up to 30 minutes. I have known there to be no adverts and only trailers. But on the screening of Inbetweeners 2 I went to there were adverts but no trailers. This must be a first. I have never known Cineworld to miss out trailers. Seemed really odd. Still it did mean the film started after 10 - 15 minutes. Just seemed unusual as it is usually the adverts that are missed out.