Why did Britain want imperial control over Myanmar?

Burma, now called Myanmar, was a British colony from 1824 to 1948. During the early 19th century the British were growing increasingly concerned with protecting their colony of India from outside invasion. India was by far the most lucrative colony of the empire and supplied Great Britain with a great deal of wealth and resources. Burma was initially conquered to protect India's eastern border from outside encroachment.
As early as the 1750s, there was limited British interest in Burma when a trading station was established at Cape Negrais. Disease and attacks from hostile natives meant that the port was never very successful. Consequently, British merchants and imperialists chose to focus their sights on bigger prizes elsewhere in the region.
In 1785, Burma obtained a border with British India after the Burmese army annexed the small kingdom of Arakan. In the 1820s the Burmese invaded Assam, north of the British colony of Bengal. This was seen as a serious and direct threat to the security of British India. The British countered with an invasion of Burma in 1824, known as the First Anglo-Burmese War. As a result of their victory, the British took over a large part of Burmese territory. There were further conflicts in 1852 and again in 1885 that led to the British taking full control of Burmese territory.
Furthermore, the British were growing increasingly concerned with the colonial acquisitions of their imperial rival, France. The French had already acquired vast territory in Indochina further east. There were worries in Britain that if they did not bring Burma into their empire, the French might do so instead. The prospect of having a French colony directly abutting India was too grave to ignore.
The main motivations of the British in conquering Burma was to subdue a troublesome nation that they saw as a threat to their colony in India and to keep the territory out of the hands of France. However, once annexed, they made use of Burma's resources, namely rice production and gemstone mines.