The ECB has always had lower base rates than the UK because of differences in the markets between UK and the major EU economies of Germany and France. The ECB has decided not to cut rates while the BoE and the Fed have made dramatic cuts. Leaving aside the intrinsic worth of the currencies (which is impossible to value) the relative change in interest rates has caused the EUR to strengthen relative to the USD and GBP. Do not be fooled into thinking that the EUR is actually a stronger or safer currency, it is not. Major industrialists in Germany have started breaking ranks, calling for the ECB to cut rates. When they do - WHEN they do - the EUR will correct.

EUR/GBP and EUR/USD have been a good ride and holders of the EUR have done well, but like any other major currency pairs they will correct for technical reasons if nothing else. If I could predict exactly when this will happen and the amount of the pullback, I would be dictating this message, not typing it but watch out for a steep correction at any time.

A downward correction does not cause a problem for small cash reserves in a currency that you use for daily purchases - if you live in Euro land you will need Euros so no harm done. However, if you are looking for an appropriate intermediate currency, which is what the OP is asking for, then the answer is much more complicated. Since he will not be spending, in the main, USD, GBP or EUR in the shops, businesses and boatyards if he transfers his funds to EUR at this time he will be converting his (weak) GBP and USD into (very strong) EUR. I think he could end up with large quantities of egg on his face and much less food on his table, which is why I suggested to him that he might consider keeping a selection of the three currencies he already holds, in the same proportions.

The issue of producer nations (commodities and manufactured products) converting from USD to EUR is more political than economic although the recent strength of the EUR gives the opposite impression. I don't think that the EUR stands a snowflake in hell's chance of being the next reserve currency. Something will be cobbled together involving the IMF and probably gold factored in there somehow, until Chindia is ready to take up the baton, in the next ten to twenty-five years.