solder a short length of copper pipe on to get up to the correct height and delete that silver compression fitting altogether - it's only there because (assumption!) the flexible pipe can't come down far enough.
I don't think it's that easy, unfortunately - looks like the flexible hose from the tap is for a different thread diameter to what the silver valve will have and the brass reduction fitting will be compression fit. I have a similar arrangement for a downstairs sink and it was a right pita to get right.
I'm guessing these are German taps (Grohe or similar) which ship with hoses that don't fit typical UK fittings.