Venting via bath waste pipe..

[littlegus]

Could any knowledgable plumber please help with some information about venting from a bath waste?

My bungalow bathroom toilet is connected direct to a drain of less than 1.5 meters so I know it does not require a vent of its own. The problem I have is that there is an internal vent pipe connected directly to the drain from which the bath and sink discharge into which is sited directly below the bath.

My question is this; If the toilet does not require a vent to air as it is fitted direct to the drain of less than 1.5 meters in depth, does there really need to be a vent to air from the bath and sink waste outlet as the drain depth is still less than 1.5 meters from the highest overflow point, namely the sink?

I would like to fit a full size bath because at present the boxed-in vent pipe only allows a short bath and I dont like to bathe with my knees in my face or my wifes come to think of it!

Any help on this bathroom dilema will be much appreciated.

Regards

Gus from Norwich