Most familiar faces on television tend to become form-fitting and fixed as the years go by, due to the various dark arts that satisfy both the talent's easily tweaked ego and a network executive's demands. But there is a notable exception to that rule and his name is Thomas the Tank Engine.
The little blue steam engine from the Island of Sodor has been a mainstay of children's television schedules since 1984 - when the initial narrator was, famously, former Beatles drummer Ringo Starr - and where once his face was so unmoving that it suggested an overdose of Botox, these days it's positively elastic. You could make that joke about having what he's having, but in Thomas's case it appears to be nothing more than coal and water.
The expressive transformation of Thomas the Tank Engine and his fellow engines, from haughty Gordon to the impish Percy, is, of course, a reflection of technology's growth. When the storybooks were first adapted 28 years ago, the producers used live-action model animation, with static figures for animals and humans, but eventually the models were put away and computer generated imagery (CGI) took over. It looks better, but the crashes are nowhere near as fun.
Depending on when you became either a parent or a heavy user of marijuana, your perception of children's television is generally keyed to a certain era. My kids are aged seven and two, so I've seen - purely in the line of duty - a lot of eight-minute episodes about brave animals and plucky English village residents (Bob the Builder, Fireman Sam, Postman Pat) during the past five years.
At one stage there were morning sessions of Thomas & Friends and evening marathons of The Wire, and while I don't want to draw too long a bow between the two shows, I have to note the similarities between railway kingpin the Fat Controller and East Baltimore godfather Proposition Joe, portly gentlemen who both appreciated the power of a cartel while having to handle troublesome subordinates.
The stories on children's television stay the same, but the intent changes subtly. The gentle New Zealand animated series Milly, Molly, for example, is about a pair of seven-year-old girls and is heavily focused on racial diversity, right down to having a child from a refugee family arrive at school.
The era when Play School and Sesame Street on the ABC were givens as the fundamentals of good television viewing for kids is long gone. With the arrival of Foxtel and niche digital free-to-air destinations, there are now entire channels dedicated to children aged two to eight (as well as nine to 12, and so on). The ABC's iview website is nirvana for a child with a tablet computer and a doona to hide under.
And then there's the plethora of dedicated channels on the pay platforms. There's more than enough to keep the kids - and everyone else - entertained 24/7.
But don't get too attached - that's the most cruel thing about children's television. Just when you have your favourite series (or at least some bearable ones) sorted, your offspring will summarily banish them from the schedule and no amount of bribery can bring certain shows - OK, The Octonauts - back.