Cans of old housepaint (Marchmont EH9)

I have a dozen or so cans, of varying sizes, part-full of housepaint. There's about 11 litres in total, in various types (emulsion, oil-based, etc.), and in a variety of colours (mainly pastel shades); some colours have more than 2 litres. The paint is old - much of it dates back to 2011 - but I recently used some of the oldest cans for retouching ceilings and woodwork, and, after a vigorous stir, they worked well, giving an exact match to the original. (No guarantees, though.) They could also possibly be suitable for some sort of artwork (web search "Steve Camps whale painting").