Bamboo- inherited

Here is a photo of a shoot that the bamboo has shot out over the last little while. We moved into this garden a year ago and it has seemed contained for the last year but now these worrysome looking shoots are emerging! Any idea what to do next. Below is a picture of it in its entirety. It is a black stemed variety I think! I would like to thin it out a bit and am worried that it may take a hold in other places. I don't think so as this is a long established garden we have moved into and I feel sure that it is contained under ground!!!!! Any help here would be very much appreciated. Thanks folks.

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Sorry about the sideways on photos but it seemed to up load like that!! If you have an ipad it keeps righting itself to be sideways on! Argg aplogies.
Are bamboos, taboo!
There's a lot of info. already here if you page down a bit. Some bamboos are a huge problem but hopefully not yours.