Lithograph music cover for 'Nightingale Music written, composed and arranged for Christine Millie, the two-headed Nightingale by William Wilson... Published by Emery, 408 Oxford Street, London and Hime & Addison, Manchester'. The cover lists seven songs. At centre a picture of Chrissie and Millie McCoy, conjoined African American twins, wearing white dresses and button boots.

Conjoined twins Chrissie and Millie McCoy (who sometimes referred to themselves as one person) were remarkable women by any standards. Not just successful women they overcame prejudice and exploitation on a number of levels. They eventually became so successful that they were able to buy the plantation where they were born. They gained money and fame through their singing career, with Queen Victoria supposed to be among their fans.

Enslaved from birth, the McCoys were bought and sold numerous times (even stolen on one occasion). They had little or no choice about the way in which they performed or were displayed. Even when they became famous singers, medical men were still able to examine them as ‘medical curiosities’. The name 'Christine Millie' shows how they were regarded as one person rather than two.

After the emancipation of slaves in the 1860s, the sisters were free women, yet chose to remain with the Smith family, their previous owners. They wrote an autobiography describing their lives, which was used to promote their singing, and thus presents interesting questions about how honest they chose to be.