Increasing space for main title in a lattice (xyplot()) graphics.

I'm trying to do an xyplot() with a longish main title that I'd like to 
split into two lines, something like

     xyplot(<whatever>,
            main="The quick brown fox jumped\n over the lazy dog.")

When I do this I only get the last half, i.e. the "over the lazy dog."
bit, and the first half doesn't appear.

In base graphics I'd handle this sort of thing by increasing the third 
entry of the "mar" parameter.

How can increase the space allocated for the title in lattice graphics?
I've done a substantial amount of Googling and can't find anything 
helpful.  I've fiddled about with trellis.par.set() and cannot seem to
get any effect.

Could someone please give my poor feeble brain some guidance?  Ta.

cheers,

Rolf Turner

Honorary Research Fellow
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276