Turkeys had been brought to Britain from America hundreds of years before the Victorian era. By 1575, the English were enjoying the North American bird with Shakespeare mentioning it in Henry IV.
By the way, the bird is called turkey in the U.S. and the U.K. because early importers wanted to coattail on the popularly of guinea fowl that were brought in from Africa by Turkish merchants. These birds were known as turkey fowl, often just shortened to turkey.
When Victoria first came to the throne however, both chicken and turkey were too expensive for most people to enjoy. In northern England roast beef was the traditional fare for Christmas. In London and the south, goose was the favorite option. Many poor people made do with rabbit (or sometimes oysters which were cheap at the time).
Turkey was added to holiday menus by the more wealthy sections of the community in the mid-19th century. When supply increased in the last half of the 19th century, the bird’s lower cost and size were perfect for a middle class family gathering. As a result, turkey became the dominant dish by the beginning of the 20th century.