According to this article:
The Prime Minister announced plans to amend the EU Withdrawal Bill to make it absolutely clear that Britain’s exit will come at 11pm on Friday 29 March 2019.
11 PM is GMT, as specified in this article.
She said the EU Withdrawal Bill would be amended to formally commit to Brexit at 23:00 GMT on Friday 29 March 2019.
While the date is article 50 triggering date + 2 years, the time seems quite strange (why not the end of day / 12.00 AM?).
It seems as it is chosen to make the end of the day one time zone ahead (CET) or maybe it is related to British Summer Time:
BST= GMT + 1h, but could not find any official reference to clarify this aspect.
Question: How was the time of Brexit computed?