I had wondered whether the Toronto side would have been given a home in Birmingham or somewhere like that in an attempt to expand the game on both national and international fronts.

Don't use London as an example. They were ran abysmally. Had they ran a club in Yorkshire, it would have been relegated.

There are plenty of examples of sport being popular, without large numbers taking part.

American Football (they can fill Wembley stadium and the game isn't really played in this country)
Tour de France (Yorkshire) Huge numbers watching a sport that has never previously had mass appeal
Horse Racing. Not too many people have taken part in this but, plenty turn up to watch
The Boat Race (the biggest load of tosh ever but, viewing and spectator numbers are huge)

Even Figure Skating was popular a few years ago.

It's all about publicity and hype, plus clever marketing

If we paid some celebrities and put an advert together along the lines of "I'll be going, will you" and gave it sufficient air time, people would turn up.

The media can generate interest in absolutely anything. For our sport, it has proved too difficult to get them on board.
As to why they are so reluctant to show any interest is not known but, with the right marketing, anything can be "sold" to the general public.

I keep reading in League Express how the amateur game in the heartlands is in a steep decline. If that is the case is there any choice but to expand the boundaries of the game? Or are less people playing in Hull because there is a club in Oxford now?

They don't show any interest because people in most of the country don't care about Wigan and Hull, and have never even heard of most of the other places where RL is popular.

We have expand to attract new people to the game and new sponsors.
We are expanding, but at a slow pace.