In 1871 the House of Commons appointed a committee to investigate the East African slave trade; Waller and Edmund Murge pushed it to recommend Sir John Kirk as permanent political agent at Zanzibar.
En 1871, a Cámara dos Comúns nomeou un comité para investigar o comercio de escravos na África Oriental; Waller e Edmund Murge impulsárono e recomendaron a Sir John Kirk como axente político permanente en Zanzíbar.