From around 1911 or 1912 until at least 1915 (after the outbreak of World War I), Ethel operated a type-writing office at this address. During 1912-1913 (according to the Electoral Register) it appears she operated two offices -- one here, and one at 3 Tavistock Street. 

This office location is listed during the years 1900 and 1905 as one of her locations. Due to its proximity to legal and financial institutions of The City of London, it is possible this office catered more to those fields, while her offices in Tavistock Street were kept busy with theatrical and literary work.

Ethel Dickens operated her typing business from this location from sometime in 1897 until sometime in 1900 or 1901. In the Electoral Register of 1897, she lists her place of work and her place of habitation as the same: 21 Tavistock Street. In 1898, she moves her place of abode to 91 Philbeach Gardens, sharing a home with Bertha, but her office remains at 21 Tavistock until the turn of the century. Around 1905, she returns to the 21 Tavistock Street premises, though only briefly it seems.