Yes they do traffic manage and specifically P2P
While I'm not a torrent user and have never been a Tesco BB customer traffic management is based on recognition of traffic patterns which the machinery can get wrong and thus throttle legitimate traffic.
As you can tell I'm not a great fan of P2P as it does place substantial loads on networks.
Virgin (ADSL) => Namesco => Newnet => O2 => Plusnet => Zen => Newnet => Zen => Freeola => Vivaciti (using O2 Wholesale DSL) => Xilo (C&W Wholesale) => Xilo (O2 Wholesale)
Note: I don't lay turf for anyone. astro or otherwise, all views and opinions expressed are my own based on experience.