And one other oddity is that Conway and Lamb are not on tge same or adjacent pages of the GRO death register. Check freebmd.org.uk
I think this might simply point to bodies lost in water and Conway was not recovered or washed up until a few days later.
There is a trial period on going with the GRO where you can order death certs by pdf. It might be of interest in this case.
http://www.gro.gov.uk/gro/content/certificates/
They wont tell you the serial number however.