Question Time is recorded in front of a live audience from around 2030 each Thursday. The reasons for not broadcasting live at 2235 are to limit inconvenience to spectators and guests (enabling them to appear on the programme at locations across the country and still return to their homes at a reasonable hour) and maximise the number of leading politicians and political commentators willing to take part in the programme.
The recording is done in a single take, precisely as if it were broadcast live. Some exchanges occasionally have to be edited out for legal or taste/decency reasons.
Any text messages sent in when the programme goes out at 2235 are live responses to the guests' remarks as they are broadcast and the subsequent text exchanges on Red Button are also live.
Guests are not warned in advance about questions to be asked.