Disco 2 TD5 - manual 04 - brake fail

ok so driving home down steepish wet slushy tarred road using gears to reduce speed given current road conditions. I change down into 2nd to make a turn and have to press brake gently to make the turn.
No brakes, just hard vibrating pedal. No option but to abort turn and continue only to find brakes kick in again. Now everything appears mechanically sound, no leaks , spongy brakes etc. Any pointers please gents?...

Traction control cutting in?

Cheers

Your ABS was operating because the wheel speed sensors believed the wheels were locking. It's normal, but disconcerting!

Thanks Gents!