One of the most striking findings of the entire survey is that younger Jews below 40 are more religiously observant than their parents and grandparents’ generation.

In almost every score — whether separating meat and milk utensils at home, attending Friday night dinner, not travelling on Shabbat or fasting on Yom Kippur — the under-40s are more religious than the middle-aged (from 40-64), who in turn are more religious than the over-65s.

This phenomenon “runs counter to a commonly accepted narrative that young Jews in Britain are less religiously engaged than older Jews,” the authors of the survey point out.

But they suggest that “at least part of the explanation may lie in the significant and well documented demographic growth… among Charedi and Orthodox Jews in Britain since the early 1990s. These groups have relatively large numbers of children and therefore exhibit disproportionately young age profiles.”

In fact, more than three times as many of the under-40s said they were Orthodox or Charedi (24 per cent) as those over 65 (seven per cent).

Sixty-five per cent of 16-to-39-year-olds attend a Friday night dinner, for example, compared with 57 per cent of 40- to 64-year-olds and 45 per cent of senior citizens.

Whereas just 10 per cent of senior citizens refrain from Shabbat travel, the number rises to 18 per cent for the middle-aged and 28 per cent for the under-40s.

On Yom Kippur, 70 per cent of the under-40s fast every year, compared to 62 per cent of the 40 to 64s, and 53 per cent of the 65s and over.

Taken as a whole, 71 per cent of all British Jews attend a Seder every year and eight per cent never; and nearly two out of three — 63 per cent — fast on Yom Kippur, while 24 per cent never fast.

More than three quarters — 76 per cent — attend synagogue at least once a year on the High Holy Days.

When it comes to regular shul-going, 28 per cent went at least once a week over the previous year, and 18 per cent around once a month, while 24 per cent did not go to synagogue.

Just over half of those who identify as “Orthodox” are at least weekly attenders, compared with almost a third of “traditionals”: slightly over one in 10 secular/cultural Jews go weekly, too.

Just over half of Jews (52 per cent) separate meat and milk utensils at home; 48 per cent buy kosher meat for home; 36 per cent never eat kosher meat outside the house. More than a quarter — 27 per cent— buy pork products.

More than half — 57 per cent — overall have a Friday night dinner most weeks, with 49 per cent lighting Shabbat candles; one in five — 20 per cent — do not travel on Shabbat and 18 per cent do not turn on lights.

WHAT THE FIGURES MEAN

The authors of the report are undoubtedly right that the rise in religiosity must be in some measure due to the population growth among the strictly Orthodox.

But could another factor also be Jewish education — with more children going to Jewish schools or attending yeshivot?

One reason for lower levels of religious observance among the older groups could also be their age. Perhaps some families are more likely to light candles and hold Friday night dinner when their children are young and at home.

Some senior citizens may also not light candles, for example, if they are on their own: or will find fasting on Yom Kippur more difficult.