FIFO treatment of shares across brokers

[abc_xyz]

So I have the shares in the same company held with two different brokers. I am selling the shares in broker B and they were acquired later than the ones held with broker A. Am I supposed allocate the purchase cost of the shares with broker A to the shares I'm selling from broker B, due to FIFO rules? Or do the FIFO rules only apply within an account?

E.g.
Got shares in broker A at €10/share in 2020
Got shares in broker B at €12/share in 2021
Selling shares in broker B - was the purchase cost €10/share or €12/share for calculating tax?

(The shares came from employer SAYE and ESPP schemes and the employer moved broker between allocations/vesting.)

 

[jpd]

I think shares are shares and where they are held is immaterial

In law, each share is equal to another - so FIFO would treat all shares as equal