I’ve got some Altura Nightvision ones that are no longer waterproof (despite reproofing) and have never seemed particular breathable either. I only want them for cycling to work and my commute isn’t that long (~5 miles). As I only ride at a steady pace on the way to work I’m wondering whether a pair of cheap (but actually waterproof) non-breathable over-trousers is the way to go? Anyone got some and regretted it? Alternatively, can anyone recommend some cheap “breathable” WATERPROOF alternatives?

google raf goretex. you’ll find them for less than 20 quid online. personally though i’d use waterproof shorts. they don’t funnel water directly to your shoes, are more comfortable/less restrictive, and are better ventilated.
but above all, if you have a dedicated commuter, just stick some good guards on it.

I’ve got a dedicated commuter (with full mudguards). Shorts are a no go as I need to keep my work trousers dry. I can’t be arsed with having to get changed after my commute (hence riding slowly) – otherwise I wouldn’t bother with waterproofs at all.
The problem I have is water cascading off my jacket and making the tops of my legs soaking wet. There’s the secondary issue of water running into my shoes, but that’s less of a problem.
Thanks – I’ll Google the RAF Goretex ones.

As above, army surplus goretex are cheap and work. The RAF ones are non camo so look OK. All come up a little big/baggy. I’ve also got some Peter Storm over trousers which are less breathable but fully waterproof and better fitted. With good mudguards you rarely need them though. Most of the wet is road spray unless its really raining.

You could try Rainlegs. They should keep the top of your legs dry, and plenty of ventilation. http://www.rainlegs.com/