tax on ST
I've answered this point much earlier in this thread, but as it has come up again - the law is that a benefit is taxable on the amount it costs the employer to supply it, not it's market value to the general public. (Company cars are a whole separate issue)
ID90s do not cost the company anything, as the 10% paid covers the cost of admin and meals, and of course the seat would have been unsold anyway.
ID100s do cost the company the cost of admin and food/drink etc, (but not the seat as even though 'firm', staff do still not get on if a passenger comes at the last minute) and BA pays tax on calculated amount on behalf of the employee. By the way, an employer paying an employee's tax bill is also taxable, and that is included in the 'settlement' the employer pays to HMR&C.