Even if it is a European coin its current price behaves in a similar way as if it was American: the prices significantly increases if the quality of the coin increases a little bit. It is very easy to find high quality 5 Pounds 1887. This makes their price very stable and predictable. In MS 61 we can see that they are commonly hammered at around $2.400 while in MS 63 they are commonly hammered at around $3.600 (one and two). There are not so many examples in MS 62, but we can take this one as a reference from November 2016. It was auctioned for 2.800 CHF. However, we should take into account that the coin that is now in auction has a “tiny edge error”. This error may have a big impact on the coin price, but I cannot judge it as it is not shown in the photographs.
Description from the seller
Five Pounds 1887. Friedberg 390, Seaby 3864. In US Plastic-Holder PCGS MS62.