The operator of the bus services in the Cascais area is SCOTTURB.
http://www.scotturb.com
Their website is not exactly up to date.
The service you require for Quinta da Marinha is the 405/415.
The latest timetable can be found here:
http://www.scotturb.com/inverno2007/405415.htm
This however does refer to the winter 2007 service.
It appears that there are practically no evening services.
