Customising a PDF file download filename?

Problem/Motivation

I have created a view which picks up a contextual ID on a path: examination-question/pdf/% pops up a downloadable PDF version very nicely.

The problem is that the file is always called document.pdf

Is there a way that I could customise that to be the title of the node (say) or better still make up my own by using tokens within my view.

I just can't seem to work out where I can even attempt to change that default filename.

Thanks all