Hansard – 1803-2005, 7.6 million speeches, 1.6 billion words. This Hansard corpus (or collection of texts) contains nearly every speech given in the British Parliament from 1803-2005, and it allows you to search these speeches (including semantically-based searches) in ways that are not possible with any other resource
The SAMUELS project (Semantic Annotation and Mark-Up for Enhancing Lexical Searches) allows searching of the 7,545,101 texts (by nearly 40,000 individual speakers)
This does not provide full copies of the texts. You would need to obtain these from the Hansard archive.