Bank of England talk about 2040 in their papers as do many other people. I always assumed 2040 was typo.
It is.
What am I missing?
Your formulae are all wrong. The block subsidy (indeed, all bitcoin values) are an integer number of satoshis (hundred millionth parts of a bitcoin), and rounded down when they would be fractional, so column C should be =(FLOOR(C2*100000000/2))/100000000 and you shouldn't be rounding column E at all (and you should show 8 decimal places). Also, 210,000 blocks is slightly less than 4 years; at 10 minutes per block, it is 1,458 days and 8 hours. For reference, a correct table of block subsidies can be found here:
en.bitcoin.it/wiki/Controlled_supply#Projected_Bitcoins_Long_Term