@simonind
It's more than possible that your brew has nearly fermented out after 4/5 days. At the correct temperature (which you have) and with the right amount of yeast many normal gravity beers are pretty much done by then. The evidence which you have is a ring of crud above the brew on the FV wall deposited by the krausen (the foam that is produced during the vigorous part of the fermentation). The only thing that is missing are bubbles from your airlock, but if your FV and the lid don't seal properly and the seal leaks, which is common, your airlock is as good as a chocolate teapot.
If you really want to find out where you are I suggest you take an SG reading. If its finishing it should be below about 1.012 or thereabouts. If its above 1.020 there is still some way to go. Either way when you have taken your sample put the lid back on and leave it for another 10 days to properly finish and clean up.
And of course all this could be wrong and your SG reading will not have moved much from the OG reading, but I think that unlikely.
