Seahorse and GNOME integration - Double click .pgp file to decrpypt

[JKL <junk4 klunky co uk>]

Dear Seahorses,

    I have reinstalled my O/S and use Gnome.  Previously, with Gnome 
and Ubuntu I had .pgp files automatically decrypt when I clicked on 
these.  I think that this was done with Seahorse.

I have tried to replicate this in the new installation, but cannot do 
it.  I would like to associate the .pgp files with Seahorse so that a 
double click with read the key and prompt for the passphase.  I tried to 
do this by informing Gnome that it should use Seahorse for this, but all 
that happened is that Seahorse was launched but it ignored the .pgp 
file.  I have spent the morning googeling for this, but found no help.

Would someone kindly offer some advise (other than telling me where to 
go:)  )

Regards, j.