UCL and KCL were the two founding UoL colleges, forming together to begin the universities federal existence in 1836. Prior to this date UCL was the original UoL (1826) but because it had no ties to religion or the monarchy King's college was set up - with the support of George IV – in 1829 to rectify this. As KCL also wanted UoL status, UCL was forced to become a college with KCL forming and sharing the UoL title. In time other colleges followed.
It must be said though that without the existence of the senate the unique specialists’ colleges of the university - School of Pharmacy, LSE, IC etc - would not exist with university status today. The whole mission of the UoL is to support a diversity of institutes, to pool together and assist smaller institutes, which have since grown in strength and probably able to exist without the senates support. Though I would find such an act hypocritical as the federal university is for a common good, to provide an enriched and dynamic academic world where the bigger colleges can assist the smaller ones and in turn have the provision of specialised research institutes to broaden and expand their research. Look at the many collaborative research projects between institutes and it is truly amazing.
Lastly, in the case of Imperial, without the UoL they would not exist, at the turn of the 20th century UoL approached three institutes - the Royal Schools of Mines, the royal College of Science, and the City and Guilds College - and suggested they pooled their strengths and became a specialised college for science and technology. This would not have been possible without the backing of the senate. How easily can children forget and lack appreciation for their parents!