You are talking about what was the norm some 60 years and more ago. Travel on business will have been extremely rare and mostly limited to managerial levels where the individual employee would have received his/her normal salary from start to finish, plus money toward expenses. Those travelling on business for a company/office they themselves owned would simply have charged their costs to it and paid themselves what the business could bear (if it was at all accounted for separately - much more recent tightening of tax laws & regulations has brought about the strict separation of private income from business income.