Wash them by hand in warm water with mild soap. The glaze on antique blue and white jugs is often crazed, meaning harsh detergents can seep into the clay body and cause discolouration. Never put them in a dishwasher. The extreme heat and harsh chemicals will strip the protective glaze and ruin the surface.

Can you still use them?

Yes, they are still functional for pouring water or serving milk. Avoid leaving liquids in them for days. Standing water can penetrate old glaze faults and stain the earthenware.

I have a large jug with a pastoral scene but I cannot find a maker's mark on the base, is it still worth keeping?

Unmarked examples are very common and highly collectable. Many Staffordshire potteries did not mark their wares during the early nineteenth century, relying instead on the popularity of their specific patterns. The lack of a stamp does not mean poor quality. Collectors judge these pieces on the crispness of the transfer print, the depth of the blue colour, and the potted shape.

There is a brown stain creeping up the inside of the spout, what causes this and can it be removed safely?

That brown staining happens when old liquids penetrate fine cracks in the glaze over many decades. The clay body absorbs the residue, leaving a shadow that cannot be scrubbed away. Some restorers soak pieces in chemical solutions to draw out the stains. For most owners, it is better to accept the marks as honest signs of historical use rather than risk damaging the glaze.