I want to know the answer to the following question:
Underground officials were ordered to lock the stations during raids but opened how long after the orders?
All the background I'm provided with is that "Although many civilians had used them as such during the First World War, the government in 1939 refused to allow the stations to be used as shelters so as not to interfere with commuter and troop travel, and the fears that occupants might refuse to leave.". Is that enough to answer the question?