This is wonderful, exactly what I was looking for! Should be suggested to the devs for official inclusion in the game, tbh. :-)

Shows expandable sections of Tier 1/2/3/4 and Faction items (you can select which sections want to show—e.g. I'm using only Tier 3/4/Faction for the moment) right below the inventory search bar in the "Possessions" tab of Fallen London.

Love the options to gray out stacks of items if you don't have enough for conversions as well (you can choose whether you want them grayed out until you can do a large conversion as well) and to gray out Faction items until you have enough Favours to up Renown.

It helps a lot with handling the grindy part of the Fallen London game ;-)