Great Western Coffee Shop

Can someone explain one mystery to me (which has perplexed me for some time). If I buy a walk-on return ticket for a long distance journey, the return journey can made within one month. However, the validity of the outward journey seems to vary. I suspect this may be something to do with different TOCs, but it would be nice to have an explanation.

An example is this (both journeys booked at Bath Spa station in the last week):

1. We booked return journey from Bath Spa to Bangor (via Hereford) and specified the outward journey day (December 23), but the ticket has printed on it outward journey can be made on any of 5 days from the date we specified (up to December 27).

2. We booked return journey from Bath Spa to Penzance and specified outward journey day (December 30), and the ticket has printed on it only valid for outward journey on that one day.

Why the difference?

I suspect the Bangor ticket is an "Anytime" and the Penzance is an "Off Peak"

Different types have different conditions

You are correct, but I'm sure most Anytime tickets I've booked (apart from those between Bath and Bangor) have only allowed travel out on the specified day.

The outward portion of an Anytime Return ticket has been valid for 5 days for a number of years now.

The Anytime Single is valid for 2 days.

There was a brief period, following 'Fares Simplification' in September 2008, when Anytime Singles and the outward portion of Anytime Returns were only valid on the date shown. This was soon changed to the 2 and 5 days we have now. Prior to September 2008 the outward portion of an Open Return was valid for one month.