The nearest match we can find is "The Abruzzo and Molise Heritage Society of the Washington, D.C. Area" but it's unlikely that they installed the Tosti plaque in London.
This section lists the memorials created by the subject on this page:
Assoc. Abruzzo-Molise, G.B.
Creations i
Sir F. Paolo Tosti
City of Westminster Sir F. Paolo Tosti, K.C.V.O., musician, 1846 - 1916, liv...
Other Subjects
Nazareth House
In 1850, Dr. Nicholas Wiseman became concerned about the plight of the aged, orphans and abandoned children in London. He appealed to a recently formed religious order in France which took care of ...
Building, Architecture, Benefactor, Community / Clubs, Religion
1 memorial
Ongar Millennium History Society
Formed to promote and foster an active interest in the local history of Ongar, and to preserve it for future generations.
1 memorial
Young Womens Christian Association
From their website: YWCA was founded in 1855 by Miss Emma Robarts and The Hon Mrs Arthur Kinnaird. Miss Robarts started organising groups for young women who were coming to London for the first ti...
1 memorial
Friends of Choice FM
We're not sure if this group still exists. Is this the group on Facebook?
1 memorial
George Green Association
We can't find any information about this group, so can only assume that it's now defunct.
1 memorial