Old switch is a standard two way switch, modern switches are the same, new switch is not suitable for the UK and is not two way, it requires a neutral which is not taken to UK switches.
The old system uses a borrowed line, the centre switch is two way, it takes its line from the top switch this is frowned on today as it can cause problems with hearing aids and the like. But not banned.
So bottom switch is suspect, line does not normally go to com with two way switching. The com is the important wire with two way, if L1 and L2 are swapped then the switch position is swapped but it still works, but com must be correct for it to work.
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