While the national census includes a voluntary question on religion that contains a ‘Jewish’ checkbox, it does not ask about Jewish denomination. This means it is quite challenging to establish whether different sub-sections of the Jewish community were counted accurately.
Of particular concern is the count of the Haredi (Strictly Orthodox) population. There are several reasons why. First, Haredim are an economically vulnerable group, and providing an adequate level of service and welfare provision to them depends on having an accurate understanding of their numbers. Second, they are a rapidly growing section of the Jewish population that today accounts for as much as one in four of all Jews in the UK, including a majority of all Jewish children. And third, linked to this, a Haredi undercount means the overall Jewish population is also undercounted. Given that Jews make up just half of one percent of the total population of the UK, this is important.