Even a relative hydrogen sceptic like me realises that it will have a role in reaching net zero. Hydrogen is a very useful building block for a range of chemicals that benefit society, none more so than ammonia which is used to produce fertiliser and help feed the planet. So our first hydrogen action should be to decarbonise current CO₂-emitting hydrogen production.

Well said, Tom. Too often a lightning rod topic like this is treated as all or nothing. You're with us or you're against us. We can't let the era of the Tweet and the sound bite need for pithiness take away from the nuance that solutions will ultimately take. 

Though your view is a welcome one, Tom - hydrogen-as-fuel is indeed 100% hype - it's even worse than you claim.

"It is not energy efficient: for every three units of energy provided by hydrogen you have to put one unit of energy in."

You have the ratio backwards. It should be: "for every one unit of energy provided by hydrogen, you have to put (at least) three in."

The First Law of Thermodynamics, which describes the conservation of energy, stipulates that energy is never created or destroyed. Energy in = energy out. That doesn't mean, however, you will get an equal amount of useful energy out. Most of the energy needed to use hydrogen as a liquid fuel, whether from steam-reforming methane or electrolyzing water to make it; whether from converting it back to useful energy by burning it, or in a fuel cell, is wasted in efficiency losses. It might be as heat created from friction between moving parts of machinery needed to compress hydrogen, or from friction between hydrogen and the pipes through which it's pumped, or energy needed  to truck it to service stations and convert it back to water in a fuel cell.
Round-trip energy efficiency of hydrogen-as-fuel depends on a lot of factors, but it's difficult to justify any number requiring two digits. Most I've seen estimate ~6%. In other words, 94% of hydrogen's energy is wasted en route.

After the introduction of GM's EV1 electric car in 1996, oil majors realized the era of liquid fossil fuels was coming to an end - that their most profitable product, gasoline, would soon be unprofitable. So they set about creating markets for natural gas, or methane, in two principal applications: 1) generating electricity with it to power electric vehicles, or 2) creating hydrogen from it to power fuel cell vehicles. Both create copious CO2 emissions. But with hydrogen, however,  they could "pre-emit" the carbon during production at refineries, so that the only emission from consumers' vehicles would be water vapor.

Though the ingenuity of oil company marketing departments is boundless, promoting hydrogen as a clean fuel could charitably be described as disingenuous, but more accurately as a scam.