As I said last time, it is important when you live right on the coast to look after anything that is made of metal. Salt and sand will corrode and abrade, and locks that would last 30 years inland will fail within 5 years in a place like Blackpool.

The easiest way to stop your locks from rotting is simply to use a smear of white grease or vaseline on the exposed metal inside the keyhole. Don’t use a lot, or things will stick to it. Just use a very small amount, then wipe it over with a cloth. This will help repel the water and keep things smoothly working.
You could also use a furniture polish on any external metal, as this too will repel and protect, while not being transferable to you and yours. Your brass will stay shiny.

For lever locks, make sure you have an escutheon fitted. These are the little flaps that drop back over the keyhole, keeping things out.