There is website with much detail on Toxteth Park Cemetery and inscriptions. Try Googling, in one word, 'toxtethparkcemeteryinscriptions', and you should find it useful.
A
got it!
Ernest BENN, / who was lost at sea 20th March 1918, / aged 28 years.
He could be the Benn (no first name) on the deaths at sea index for 1918, on the Olympic, I believe it was used as a troopship, googled it and can't find any 'action' on that date so he wouldn't have been eligible for a war grave.
His mother's name on the inscription matches the Ernest Charles Benn from the census returns (Bean in 1911!) so I think it's him... may spend some cash and look at the mercantile marine record to see if that ties in too.
Thanks a lot everyone, good spot Ainslie!