When the BBC started doing the Shakespeare plays in which we on the other side of the pond were privileged enough to see, they did a wise thing in having the same actors play the same characters giving continuity to the plays. All of the people from Richard II whose roles were repeated in Henry IV got to do their parts again. Most important was Jon Finch who as Bolingbroke usurped the crown from Richard II in the previous work and now is Henry IV in both Henry IV Part One and Two.
In this production Finch is finding out what it's like to be king as some of us supporters are now disillusioned with him. Most prominently the Earl of Northumberland and his son Henry Percy known as Hotspur for his skill as a fighting man and a rather quick temper. They're gathering some similarly malcontented people to their cause in overthrowing the king they feel was not up to the job.
Henry IV had several sons and what happens with them is the subject of several succeeding historical plays Henry V and the three parts of Henry VI as well as Henry IV Part Two. The oldest is Prince Henry known as Prince Hal. Instead of helping dad out with running the kingdom, he'd rather hang around the taverns with such low born folks as John Falstaff and have a rollicking good time.
And playing Hal one of Shakespeare's most popular characters is David Gwillim. He gives a splendid interpretation of the part, playing nicely against both Finch as his father and his older companion in merriment Falstaff who is also fully realized in character by Anthony Quayle. This character proved so popular back in the day when he was created in both Henry IV plays, Master Will Shakespeare was forced by public opinion which meant then the lords and ladies and titled folk who saw his work to create a separate work around Falstaff with The Merry Wives Of Windsor. It's a great part for one to give full range to the emotions. Falstaff is a braggart and a liar, but he does it with such aplomb that you can't help liking him. In fact the character in a modern guise appears in My Own Private Idaho where parts of Henry IV Part One and Two are used in Keanu Reeves's dialog who was Prince Hal in that Gus Van Sant classic.
The fun loving Hal is contrasted with Henry Percy who is played with fire and passion by Tim Pigott-Smith. Hotspur is a character you see recur in many of Shakespeare's work, a single minded hot head like Tybalt in Romeo and Juliet and Laertes in Hamlet. He's contemptuous of Hal, but when the time comes Prince Hal shows dad and the audience he has the right stuff.
Henry IV Part One follows in the same excellent tradition of Richard II. At some point I would love to see all the BBC Shakespeare plays from this series and hope they all maintain the same quality.