This looks like a better advert for the forthcoming exhibition and gives dates more clearly:
From the Guardian...
From 'druidical erection' to Spinal Tap: a history of Stonehenge as tourist site
New ‘Stonehengiana’ exhibition created by archeologist Julian Richards displays souvenirs and other ephemera charting history of site as tourist attraction since the 19th century.
Wish You Were Here opens on 1 May and runs until March 2016. Admission is included in the Stonehenge entry price.
http://www.theguardian.com/uk-news/2015/apr/30/from-druidical-erection-to-spinal-tap-a-history-of-stonehenge-as-tourist-site
Something is not right. This message is just to keep things from messing up down the road