Hi,

When driving over traffic calming bumps  the suspension squeaks and squelches. Am I right this is from the perishable parts like bushes that are basically 19 years old? In warmer weather it’s less pronounced.

Anyone have  experience of this?

Yep I'd say bushes. A good place to start would be the suspension arm bushes. 

Finally managed to get the suspension looked at, not yet perfect but had the lower suspension parts replaced. The knock has gone. May need the upper arms (?) replaced. The improved situation does vary depending on what mode the suspension is on. Interestingly Dynamic setting gives the least creaks compared to Auto & Comfort settings  

Glad you've got partly sorted 🙂