I’m not sure what time period you had in mind. Unions and union membership have changed greatly over the years. I’ll assume you’re talking late 19th, early 20th Century.
From bits and pieces in the London Times the Shipping Clerical Staff Guild was formed in 1919, ‘to protect the interests of shipping clerks as to hours, conditions, salary, etc”. In 1921 the London and Liverpool Guilds were amalgamated and became the Shipping Guild and ‘will cater for administrative, clerical, and supervisory employees, including practically all non-manual workers engaged in shipping’.
Here’s a limited preview of a book on Victorian Clerks, published 1976. You’ll read there that it was the shipping companies and some other industries in Liverpool that employed large numbers of clerks and that the vast majority of clerks worked for small companies or individuals in very small offices. It also says that most clerks’ unions were relatively weak and unsuccessful before 1914.
http://tinyurl.com/3mugqb3I think the shipping unions were more likely intended for those working for shipping companies, where there were large numbers of workers, rather than for employees of individuals.
Askan
