What time was it in Ypres?

[Guest]

This is my first posting on this forum - I hope it's in the right place - please move it if it isn't!

Several years ago, whilst researching my local war memorial in Balderstone, Rochdale I was surprised to find that the single day when the most men died (5) was the 6th of September 1917 rather than, say, the 1st of July 1916 or the 31st of July 1917. A lot of looking up in books allowed me to find that this was the result of an attack by 1st/5th and 1st/6th Lancashire Fusiliers in an area of the front just north of Frezenberg, near Ypres.
I've decided to go and pay my respects, as close as I can to where they were, on the 100th anniversary of what was a very black day for Rochdale and its neighbouring towns. I'd like to be there at the time they went over the top, 7:30am.

There my difficulty arises. In 1914, like much of Western Europe, Belgium was on GMT. The parts occupied by the Germans were moved onto Central European Time (GMT+1) where, in winter, they have stayed with GMT+2 used as Summer Time (where they will be of the 6th September 2017). In 1916 the UK moved onto GMT+1 Summer Time (where the UK would, I think, been of the 6th of September 1917). 

I've done a fair bit of searching but can't find an answer to my basic question which is "What time were the battalion war diaries in Ypres (which is, I assume, the source of the 7:30am time) written in? GMT or BST or, even, CEST?"

[David_Underdown]

The same as British time - even France only permanently adopted GMT+1 post the Second World War (well, it was introduced by the occupying German forces, and they never switched back).  So as BST in September

[Guest]

Thanks.