"Sen Trade Unionism would never sanction more than one big strike at a time with all the other trades working overtime to support it."--Bring out the context and elaborate it.

Answer: This sentence belongs to G.B. Shaw's essay "Freedom". Trade unions are formed only to protect the interest of the workers. It is always seen that the masters or the employers of any mill or factory torture, exploit their workers and very often they throw out workers from their job at any time. Being jobless, the employees have only one option open. They only can complaint against it to their trade union. And the trade union has one weapon that is strike. That trade union declares strike against the employer and stops working till the employer accepts their demand. 

The writer has also told us about general strike of workers that is held by all trade unions at the same time. According to him it is nothing but a folly because the workers who stop working, must have extra money to spend those unemployed days. But as they don't have money, The other workers of different trade union have to work overtime to support the workers striking for demands. So the trade union should never sanction more than one strike at a time.