You still hear people claiming that in the 1930s BBC newsreaders wore dinner jackets to read the news. This makes them sound silly and pompous: but the fact is that the newsreader was also the Duty Officer, and welcomed visitors to Broadcasting House : they would have expected him to be properly dressed, and in those days 'properly dressed' in the evening meant dinner jackets, not an ordinary suit. It had nothing to do with the news.
Everyone else wore suits and ties, including the engineers buried away in the Control Room. To turn up in a sports jacket - or worse, without a tie - would have been considered completely unacceptable.
Even when I joined the BBC in 1961, working in the Control Room at Bush House, a certain formality of dress was still expected though suits were no longer expected. Even in Control Room (where we had no contact with the public or contributors) we were expected to wear jackets and ties. Indeed a memo came round every summer about not wearing open-necked shirts, couched in terms that made me want to take my tie off immediately.
When I became a Studio Manager in 1968 the general rule was that you should dress neatly, if not formally; though it was suggested that men should have a tie available in case they were asked to handle a programme including a visiting dignitary such as a foreign Prime Minister. Ladies were expected to wear skirts - trousers were allowed only on night shift.
As the years went on things were relaxed; nowadays people are simply expected to be reasonably tidy. Even Engineering Department became more relaxed. However some years back, when some formality was still demanded, one member of the Maintenance staff was told off for not dressing smartly enough. The next day he turned up in a kilt - he was Scots and the kilt bore the tartan of his Clan which he had a right to wear, and which was to him the correct formal dress. He wore this for some weeks: his bosses didn't like it, but there wasn't a thing they could do about it.