Well its definitely not Japanese knotweed, looks a like a version of bindweed, which is good in a way, because it means its getting through gaps somewhere underneath or outside the house. I think someone else already said these sort of plants will squeeze through any entry points and appear inside a house if they can. If your property is council owned, they should establish where the gap/s are that its getting through, and seal those up, which might not be easy. Japanese knotweed would have been a lot worse to deal with, but even so, getting your council to deal with this might be a difficult process. You should find the plant stops growing shortly, but will reappear next year if nothing is done.

Bindweed, or Russian Vine at worst but both manageable. Russian vine will probably still be covered in clusters of white flowers.

You should be able to see the plant somewhere outside. Cut it back as close to the wall as possible and then pull through from the inside. Spray the plant with glyphosate - assuming that you don't want to keep any of it - or prune it and keep it in check.
Plug the gap that it got in through. I'd be very surprised if your council did anything, unless it's a council-owned property then they may come out to do the repair.

Urbanite, as Glips mentioned the council 'not knowing what to do', I assumed that meant a maintenance person had been sent out to examine a problem with a Council property, rather than an environmental health person from that Council department looking at a private property. Mostly based on it being more likely that the maintenance man wouldn't have a clue, but the environmental person would... might not be right though;-)

Wow ... interesting ..

I have try it find it outside but can't also the one by my front door which is the same all I have there is 2 solid thick steps and a concrete path. I have never had this before, it's a old house. The people before us lived here 51 years.x

You could try this: cut it all off for now. If and when it reappears in the spring allow it to get a reasonable number of leaves and then spray it with glyphosate, or even Deep Root Killer (protect walls and carpet). Every time it reappears do the same and it should get despondent after a while. This might be a case where you would find it more convenient to use the new glyphosate wipes. But if a plant is getting in then damp could follow and needs sorting before your skirting boards rot. Might even be worth removing a section of the skirting board to see what's going on behind it.

Sorry Glips but there must be a plant somewhere! Try looking over the neighbours if it's not on your property. Even Russian Vine has limits as to how far it can travel and there will be some evidence of it above ground.

If it's something that has self seeded then its natural tendency would be to grow towards the light by the path of least resistance - that doesn't usually mean growing through walls and nowhere else. Have a good look around.

You could just let it grow until December and hang some fairy lights and balls on it ;o)

... don't forget the Christmas fairy on the top ;o)

That's what my friends say I should decorate it at Xmas.xx
Urbanite.. I do have this all over my front and back garden. I have tried to find the source of this plant outside so I could pull it out of the wall but it either under the house or really really deep as I can't find it.x

If it's "all over" then don't try to find the source just spray/pull it all up where you can - you'll get to the main stem eventually. Presumably you don't want to keep the outdoor parts of it either.

It does sound like bindweed. Could you put a photo on of the stuff that's growing "all over the garden" so we can confirm what it actually is?

I imagine, Steragram, that the stuff growing outside is the same as what's in the picture above - looks like a type of bindweed or, as Urbanite suggests, possibly russian vine.