The “art glass” items made at the Philips factory were made by the glass blowers who made the components for the radio & TVs. They normally made TV tubes and valve casings etc, but when they made a few of these art items in their spare time, they proved quite popular with the staff. The art items were not made generally available to the public and could only be got by or through staff members. The set of swans you have purchased came to me from an aunty who worked at Philips during the late 60s & early 70s. The social club used to sell batches of the glass wares to raise money from time to time. They are quite appealing but are distinctive in their rather thick and chunky appearance, and sometimes slightly rough cut from the blow pipe.