My bath plug/drain has suddenly blocked, what might be the cause?

[krashd]

Firstly, I already have a fair idea of what I need to do to fix the problem (I hope plunging will fix it, I just need to buy one), I would just like to know what sort of thing can suddenly obstruct the pipe that my bath drains to.

The problem...
Normally someone can have a bath and then pull the plug and the bath would empty in 20 or 30 seconds, now (and it happened almost overnight) it can take around 15 minutes for the bath to drain after pulling the plug out. Nothing goes down the bathroom bath and sink other than water and soap, and whenever there has been hair in the plughole it gets removed by me. I could understand this happening in a kitchen sink if food scraps go down the drain or someone foolishly pours grease into it, but this is my bath...

I can't for the life of me figure out why a blockage would come out of nowhere and I'd like an expert of blockages to tell me what it might be, a fungal growth? A dead animal?

I'm in the UK by the way, if that rules out snakes or other critters that have been known to traverse waterworks.

 

[Deleted member 120897]

Hair and soap scum buildup.

 

[adonis]

I use a tightly folded piece of wire or a paperclip and twist it around each hole it the waste, you will be surprised what comes out.

 

[snowhead]

Despite your best efforts, hair, from all parts of the body, skin and soap will conspire to congeal in the waste pipe.
Usually it will collect around the inside of the pipe and or on the bends and will slow the flow slightly.
Then randomly it can break away and jam and cause a full or nearly full blockage.