Sorry Paul, posting from my phone was not a great idea.
A better explanation - this is the usual BBC process, though there are some shows which just roll on from year to year, like the News. (The other channels work in much the same way).
Step one happens when the senior suits decide on their big picture, based on the audience figures, what the competition is up to, and any good ideas they' fancy pursuing - oh, and the budget - etc.
From this they decide what they want to commission over the coming year. Some of this will be specific (a major strand on underwater cookery, perhaps), and some more general (such as fewer reality shows or more costumer drama, or more reality costume dramas).
This structure will, we hope (now that at last our music seems to have snuck onto the agenda), include a number of folk programme slots, probably - as things stand - under the BBC4 Sessions brand. They may also give a steer on what folk content they'd like to see in general music strands like Later (not sure about this, it could be left to the producers).
This strategy is then made known to interested parties - i.e. programme-makers, including the BBCs in-house production teams.
These providers then submit proposals on a competitive basis to fill those slots.
The closer they can get to the required strategy, (and the cheaper too, obviously), then the better their chances - and if they can manage to tick a few bonus boxes too then so much the better.
Sometimes a new broom gets the work, but more often than not, for obvious reasons, its the incumbent - or someone with a proven track record in that field who is well known to the department concerned. Outsiders run the risk of having their ideas rejected only to see an almost identical programme being made by the in-house team or regular supplier - who, it emerges, just happened to submit an almost identical proposal. (Next time I see you I'll tell you a tale or too from my own experience that will curl your hair right up).
Now, there is no rule to stop anyone submitting a programme or strand idea at any time, but the commissioning team who receive it will merely look to the strategic plan and see if it posts through any of the slots (with or without a minor or even very major tweak, such as, perhaps, silly costumes).
If it's a really really strong idea that happens to strike a chord up the chain, it even might go on the pile to be considered for the next round, but the commission could still go to someone else on the way back down.
There are people who will, for a substantial sum, take the relevant people out to lunch and whisper in their ears - but I can do that for myself, and the truth is that because the folk world is quite small, the slots are quite few, and the existing providers very good, there's really no point in me doing so, and certainly no point in me paying someone else to enjoy the meal.
I have in fact got a short list of folky ideas, and a couple of months ago I did do the lunch thing, but I did not come away from that meeting inclined to invest any time or tears on folk shows - for the moment, anyway.
It's not like planting seeds in a big open field. It's like hoopla with one ring from the back of a scrum.