London Fire Brigade said it received 124 x 999 calls during the strike period, and contingency crews attended 17 incidents in the capital, including the large fire at a Dagenham scrap metal yard.
A recall notice was issued to crews due to the scale and seriousness of the Dagenham fire, which was ongoing as the strike started.
The FBU immediately advised firefighters that they did not agree that the protocol could be invoked and to ignore it.
Emergency cover was provided from 13 strategic locations by 27 fire engines and around 200 Emergency Fire Contingency Crew staff.
More top news
Resham Khan suffered 'life changing' injuries when she had acid thrown at her through the window of her car.
Around 20 households are still in the blocks this morning and are now being told they 'must leave' over fire safety fears
The London grime star called for the Government to be 'held accountable' over the disaster