I have been probing a bit online and expanding my knowledge in the family tree developed by my Uncle from information in the old Ager family Bible and research that he did around London.
I have found this link where two Ager brothers; Dr Frederick (1792-1851) and Henry married two Silberrad sisters; Helen Eliza (1810-1856) and Amy (1796- )
As far as I know there were 11 childeren of the marriage between Frederick Ager and Helen Silbarrad.One of them, Albert Ager (1844-1924) was my Great Grandfather and he was one of the brothers of Loise Ann Ager (1837-1918) the ancestor of Linda Marsham.
Two of the other brothers, Frederick Birch Ager (1830-?) and Sidney Charles Ager (1835-?) emigrated to Australia and family tradition has it that they went to a gold rush and were never heard of again.
The Henry Ager that married Amy Silberrad had four children of which one was called Henry.The younger Henry Ager was born in Peckham, London and baptised in St Giles Camberwell on 31st Jan 1827.He married a girl called Elizabeth and at some point was a Clerk to a Timber and Iron Merchant.This sounds similar to the ancestor of Ian Algar who emigrated to Australia.Henry Ager (the father) was a ship captain and sailed to australia several times as the Master of Convict ships.In 1842 there was a tragedy when his ship The Waterloo was wrecked in Table Bay with huge loss of life.
I also have a little information about the ancestors of Penny Fergusson's husband.Richard Silberrad (1802-1871) marroed Sarah Ann (1805-1869).As far as I know they had two children, Arthur and Emma.Emma married Sir John Wyndham.
I look forward to hearing if you think this information matches your relatives.I have some more on the Ager family tree and a little on the Silbarrads if you are interested.