How valuable is time? For a medium-sized company, let's assume:

Trainees = GBP 500 per day
Trained staff = GBP 1,000 per day
Junior manager / technical specialist = GBP 1,500 per day
Middle manager / subject-matter expert = GBP 2,000 per day
Senior manager = GBP 3,000 per day
Board member = GBP 3,000+++ per day

A longhaul J flight buys productivity, either because the passenger has slept on an overnight flight and can work over the next days or because they arrive more relaxed.

There are two flights in a return ticket. Let's assume that each way the passenger gets a full day's productivity over what they would otherwise achieve from business class travel. Then for trained staff it is worth paying an extra GBP 2,000 over the economy fare for business class travel. For junior managers that increases to GBP 3,000, GBP 4,000 for middle managers and GBP 6,000+++ for more senior positions.

In my experience F travel buys an extra half day's productivity, so for sufficiently senior people the fares can be worth it.

If you look at it this way, then all of a sudden the business class fares look comparatively good value.