Bryn,
Mine did the self same thing used to rattle its 🙆🏻 off, I changed all the followers and it still did it (but did go quite after a while) what I found was the oil pick up pipe touching the bottom of the sump pan, the oil pressure remained good cos its measured at the bottom & not the top of the engine, bent the pipe up off the bottom of the sump pan problem gone, hope this helps
Neil