L. latifolius is not scented unfortunately.

As I recall Lathyrus Latifolius does not have much of a scent. It is also regarded as a bit thuggish in gardens and more often than not is called a weed.

For scent try Lathyrus odoratus.

If you are intent on Latifolius keep its roots in a shady, damp bit of soil and let it grow into the light.

Thank you Owdboggy for your reply. It is the everlasting sweet pea (L. Latifolius) that I want, Fractal_Cat, but thanks for replying. I already have the red and white one but on visiting a National Trust house last year I thought I saw a dark purple one that was scented. I guess I will have to revisit the house and see what it is. Thanks again for your replies.

Have a look at this site, you may be able to find the Lathyrus on it.
http://www.lathyrus.info/

Winnie, if it was a perennial sweet pea and its scented, I'd like to know its name too please!

There are several other species of Lathyrus that are rarely seen now, but are likely denizens of an historic garden.