On Tuesday night, I took my seat in a packed auditorium at my local arthouse cinema, the Curzon - as did Beatles fans up and down the country at their local arthouse cinema - to watch Martin Scorsese's five-years-in-the-making feature-length documentary about George Harrison, Living in the Material World. 

It is a magnificent achievement; in cinemas for one night only, it's due for DVD release on 10 October, and an airing on BBC2 in late November. I hope the latter won't be edited down for TV, for it runs at just shy of three-and-a-half hours.

This is, frankly, too long to be sat in a cinema. I actually think that Scorsese - and by extension, George - earn every one of those 208 minutes. But as a general rule, two-and-a-half hours is quite long enough to be sat in a fold-down seat, no matter how generous the leg room and armrest-width.

(As another general rule, the seating in local arthouses does tend to be an improvement on the cattle pens most multiplexes are fitted out with - and don't mention "premium seating", with its outrageous surcharge!)

Living in the Material World does have a natural halfway mark, where an interval might be inserted, but the Curzon boldly chose to ignore it. (Actually, had they not done so, many patrons parked in the nearby car park would have had to bolt early in order not to be locked in overnight.) 

My first experience of an interval was when I saw Cry Freedom at a local fleapit in 1987. It's actually only 157 minutes long, so I'm not sure why the cinema felt the need to supply a "comfort break". It's a danger, as it can break the spell of the fiction.

The Lord of the Rings trilogy saw no need for intervals, and the first film was 178 minutes, the second 179 minutes, and the third a whopping 201 minutes - not far off the George Harrison running time. (Longer versions appear on DVD.) 

I enjoyed all three films, but they are something of an endurance test as a result. What always impressed me about the Harry Potter films - which come in at roughly the 140-minute mark, with the Chamber of Secrets indulgently tipping 160 - was how they kept an audience of small children transfixed for such a long spell. The truism is that modern kids have no attention span. Not true when Potter is minding them.

The longest film I've ever seen is Claude Lanzmann's landmark 1985 Holocaust documentary Shoah, essential viewing at 565 minutes, or nine-and-a-half hours. It was premiered on TV in 1988 but over two nights. On this occasion, I was transfixed, albeit without a smile on my face. In any case, watching something long-form at home is quite different to watching it in the cinema, where pausing and tea-making are not an option.

All credit, then, to Martin Scorsese, for keeping me not just interested, but actually smiling, for three-and-a-half hours on Tuesday.