Bankers needed their rest...
Did not know that. Did working class people take the weekends off? I suppose not, maybe Sunday?
The point was that until the 1840s, Britain was largely an agricultural and rural society, not an urban one. That tipping point was reached in the 1840s, when Britain became the first urban society in the world.
Thus, the agricultural season, that is, sowing, growing, and harvesting season regulated how most people lived their lives.
In turn, as the program explained, for a variety of reasons, people got to take a long break at winter. The days were short, natural light limited, the ground was hard, nothing grew, the harvest would have been saved months earlier and whatever bottling, pickling, and preserving, had been done, likewise, would already have been well done, and stored, months earlier.
So, as no work anyway could have been done, and, as agricultural work (in the absence of mechanisation) was back-breaking, people needed a break, and it made sense to have that break at Christmas.
Re bankers, and holidays, - although the programme didn't go into the reasons why there were so many Bank Holidays (or public holidays) in the middle of the 18th century, I would be willing to hazard a guess that these were the inheritors of the Church Holidays of the Middle Ages.
There were a great many feasting - and quite a few fasting - days in the annual calendar in the Middle Ages, but, with the Reformation, the religious justifications for such holidays were rendered redundant. However, I suspect that the holidays remained - it would have been very unpopular to abolish them - and were simply re-branded, or labelled differently.
Classical capitalism, or the imperatives of capital, commerce, profit and mechanised production (i.e. factory timetables) - and political pressure from business owners (in the form of the Factory Acts) seem to have put an end to the numbers of public holidays (that very word contains and gives clues to its own historical ancestry) that were permitted, or sanctioned, each year.