Last Night's TV: Wallis Simpson: the Secret Letters/Channel 4<br />Timothy Spall: Back at Sea/BBC4

Wonder what the Queen was watching last night? We know already that she's a big fan of Timothy Spall, so she may have kicked back at 8.30 with the second series of his amiable circumnavigation of the British Isles, Timothy Spall: Back at Sea. But when that finished did she get the butler to come in and flick over to Channel 4 for Wallis Simpson: the Secret Letters? She must have been slightly interested surely, and I can't really see her watching Sebastian Coe on Who Do You Think You Are? instead. Or ITV2's repeat of Benidorm. What's more, if she did watch, what did she make of it, having grown up with a less than forgiving view of its subject matter?

There's no real point in making a Wallis Simpson documentary these days unless you make it a revisionary one. Channel 4 ran another one several years ago, which argued that the king was effectively the victim of a constitutional coup and Wallis was just a useful excuse for levering him off the throne. But last night's film took a more personal tack. Based on private letters recently discovered by her biographer Anne Sebba, it argued that Wallis had become trapped in her relationship with Edward, only realising too late that the man she truly loved was her husband, Ernest.

She'd certainly written letters of great tenderness to him both before and after her divorce: "I miss you and worry about you," she wrote to him from Felixstowe. "Oh dear... wasn't life lovely and sweet and simple." And then, after the abdication crisis, this: "Ernest, my dear. What can I say when I am standing next to the grave of everything that was us." Ernest was no slouch himself when it came to a poignant goodbye: "I know that somewhere in your heart there is a small flame burning for me. Guard it carefully, my darling, and don't let it go out if only in memory of the sacred lovely things that have been. Someday I pray God will fan it into a blaze again and bring you back to me." Noël Coward couldn't have done much better really.

To take these messages as conclusive evidence that Wallis didn't love Edward would require a rather naive conviction that people can't be in two minds at once – or that Wallis hadn't simply been temporarily terrified by the public furore that surrounded her relationship. We can't know for sure, even now, though Sebba certainly made a believable case for an affair that started in knowing frivolity (the discreet bedroom swapping of the upper classes) and ended in a cul-de-sac out of which Wallis knew she couldn't reverse. Though she tried to break off the relationship, Edward threatened to kill himself if she did: "What a bump I'll get when a young beauty appears and plucks the prince from me," Wallis had written to her aunt in more insouciant days, quite at ease with the ending she thought was inevitable. What a bump she must have got when she discovered the story was to have a different twist.

It's not hard to see why Her Majesty would like Timothy Spall: Back at Sea. Here is a man who does for fun what she has do out of obligation – visiting various parts of the realm and rhapsodising about its beauty and diversity. He's now reached the Irish Sea and the recipe is essentially the same one that proved so successful in the first series – a lovely mix of fretful seamanship and intense pleasure in small things: "We came here across the Irish Sea! Like Vikings!" Spall enthused, after making it to Northern Ireland, which would only really have been true if the Vikings spent most of their sea crossings worrying about bumping into other ships.

If you'd thought he might by now be more blasé at sea you'd be wrong: "As my experience increases, my nerves seem to increase exponentially," he said, "The more I know, the more scared I get." Hazards in last night's episodes included unexplained bangs as they entered a Naval firing range ("You should be OK," advised the local coastguard, which didn't sound nearly unequivocal enough to me), and a passing tanker that didn't seem inclined to give him right of way. High points included the Crown Liquor Saloon in Belfast, and Spall's unhurried and ad hoc commentary on what he's up to. As his converted barge headed for Scotland, cutting through the waves with all the grace of a pig trying to climb into a hammock, he said, "It's like being drunk without the pleasure." But you knew he didn't really mean the last bit.

t.sutcliffe@independent.co.uk