//...it's not clear that it was a Jewish wedding.//
You can believe me (or not, no real bother) it was a Jewish Wedding. I know Stamford Hill very well, I know Edgerton Road where the school is and I know the school. Few people other than those from the large Jewish community living there would even know that the school hires its premises for functions; few people other than those from the large Jewish community living there would think of using it for a wedding; few people other than those from the large Jewish community living there would actually do so. More than that, it is extremely doubtful that the school (or whoever they say they sub-contracted it to for hire purposes) would consider renting to anybody other than people from the large Jewish community living there.
The Jewish community in Stamford Hill is one of the most insular and private you might encounter in mainland Britain. They have their own schools, their own shops, their own hairdressers, their own doctors, their own clinics. Gentiles do not use these facilities. The area has (when I last looked) approaching 100 synagogues - an enormous number for such a small area but many of them are small affairs, often in people's houses. It also has many small schools (most of them in converted large houses - the one where this incident is said to have taken place is an exception, being a large, purpose built establishment). The people are mainly Hasidic Jews and wear distinctive clothes. I believe Stamford Hill is the largest settlement of Hasidic people outside Israel and New York. Believe me, it was a Jewish wedding.