Why did the British choose to hold a grand Durbar in Delhi although it was not the capital?

Though Calcutta was the capital of the British but they were aware of the importance of Delhi.

Following causes were responsible to this:

(a) The British were fully aware of the symbolic importance of Delhi. During the Revolt of 1857, the British had realized that the Mughal emperor was still important to the people and they saw him as their leader. It was, therefore, important to celebrate British power with pomp and show in the city, the Mughal emperors had earlier ruled.

(b) In 1877, a grand Durbar to acknowledge Queen Victoria as the Empress of India was held in Delhi.

(c) In 1911, when King George V was crowned in England, a Durbar was held in Delhi to celebrate the occasion.

(d) The decision to shift the capital of India from Calcutta to Delhi was announced at this Durbar.

British did all this just to show the ultimate power and supremacy of British to the people of India.