Across the majority of Sunday’s newspapers, front and back, there were pictures of trippy smiles and clenched fists following England’s 169-run first Test victory over Australia – a recognition of the Ashes’ pre-eminence over even Wimbledon in the sporting summer. Yet one thing was missing amid the exhilaration and joy at England’s win: the wider audience the contest deserved.

Sky Sports guards its viewing figures closely, but I have discovered that Saturday’s enthralling final day had a TV audience of 467,000. To put that into context, a 1974 Columbo film – shown on ITV3 at the same time as Joe Root took the winning catch – attracted just under 400,000 viewers. Friday’s Sky ratings were lower still, with only 340,000 watching.

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You could argue the Wimbledon ladies’ final dented those numbers, and possibly the fine weather too. Perhaps, but it doesn’t alter the broader point. Cricket in England is viewed on TV by fewer eyeballs than it once was. Remember the light-headedness after England went mano a mano against New Zealand on a staggering, swaggering final day of their first Test in May? Some even talked of it revitalising Test cricket. But Sky’s audience was 577,000 – fewer than the one-sided Championship play-off final between Norwich City and Middlesbrough which attracted 757,000 viewers. Given that about a million tuned in to Channel 5’s Ashes highlights, there is still an audience for Test cricket. But it appears to be declining.

Babatunde Buraimo, a senior lecturer of sports management at Liverpool University, says the average Channel 4 ratings for live coverage of the Ashes in 2001 was 1.11m. In 2005 that rose to 2.5m, with an astonishing 8.4m people transfixed by the climax of the fourth Test. Cricket really did grip the nation: at one point 48.4% of those watching TV were watching the Ashes.

We know what happened next. Home Tests moved to Sky. And while the England and Wales Cricket Board swelled its coffers, viewing figures tumbled. That was not surprising – in 2005 all cricket’s planets aligned. A year later you could have put Test matches on prime time BBC1 hosted by Ant and Dec, with national lottery numbers drawn during tea, and ratings would probably have suffered an Ashes hangover.

Even so, while the data is incomplete – Buraimo does not have all the figures for the 2009 and 2013 Ashes series because Sky do not make them public – there is a worrying pattern based on Broadcasters’ Audience Research Board (Barb) numbers.

In 2009 there were 14 occasions on which Sky’s live Ashes coverage made the top 30 weekly ratings for non-terrestrial stations. The figures, of between 670,000 and 1.1m viewers, were healthy too. Yet in 2013 only two sessions attracted more than 650,000 viewers and made Barb’s top 30. We may only have had one Test, but the 2015 series is not bucking the trend. That is not a reflection of Sky’s excellent coverage, rather simple economics – more people watch stuff when it is free – and the slow unshackling of the public’s devotion to the sport.

It is hardly encouraging either that fewer adults also appear to be playing cricket. The first Sport England Active People survey, conducted between October 2006 and October 2007, found 380,000 people aged 16 or over played at least once a month during the season. In the most recent survey, published last month, that figure had fallen to 259,200 – a decline of 32%. Other team sports’ participation levels are declining too, including football and rugby union, but cricket’s have fallen harder.

So what can be done? To some there is a simple answer. Move the clock back to when home Tests had to be shown on terrestrial TV. I am not so sure. Would the BBC, ITV or Channel 4 really free up their daytime schedules for cricket on 35 days each summer? Sky’s deal is also worth £65m a year to the ECB. Lose a significant chunk of that and the sport would suffer.

But wider exposure is critical. How many of us over the past 50 years have become fans by osmosis, watching Test matches on television because there was little else to do during the summer holidays, before becoming drawn in by its nuances and peculiarities? And while the ECB argues that organisations such as Chance to Shine attract youngsters in different ways by running taster sessions in primary schools, if kids don’t know Joe Root from Joe Bloggs then the chances of them persevering with the sport are surely less.

So something needs to happen. And the questions the ECB should be asking are not difficult ones. What works? What doesn’t? Do young people really identify with county sides in the 21st century? And can the ECB strike TV deals that enable more people to watch cricket without a slump in its revenues?

It is surely not beyond the ECB’s wit to devise a domestic Twenty20 tournament with more glamour and spice. Why not borrow some of the tricks of Australia’s Big Bash, and show one game a night only split between BBC and Sky? Why not find a way to include England’s players and the world’s best stars – you know, the players fans actually want to watch – even if it means blocking off the calendar for three weeks so that no England matches are played during that time? It’s radical, yes, but the status quo is hardly working.

As things stand English cricket is in danger of becoming a sporting version of the Church of England, with an ageing demographic who attend because they always attend, and believe because they have always believed. Meanwhile younger generations will barely notice its slow and graceful slide into irrelevance.