Please answer a question about the following article about Queen Victoria:

Victoria married her first cousin, Prince Albert of Saxe-Coburg and Gotha, in 1840. Their nine children married into royal and noble families across the continent, tying them together and earning her the sobriquet "the grandmother of Europe". After Albert's death in 1861, Victoria plunged into deep mourning and avoided public appearances. As a result of her seclusion, republicanism temporarily gained strength, but in the latter half of her reign her popularity recovered. Her Golden and Diamond Jubilees were times of public celebration.

What was Victoria's unofficial title?
the grandmother of Europe