Note:
(a) "旅居美国"? Somehow I always thought he lived in the mainland. I just read zh.wikipedia.org, which only says, "2012年10月起，受邀成为香港中文大学人权与公义研究中心访问学者."
Yet his twitter, under his name, indicates "哈佛法学院访问学者."
twitter.com/tengbiao
(b) "滕彪当天在伦敦国王大学法学院开讲"
(i) King's College London
en.wikipedia.org/wiki/King%27s_College_London
(public; King's is arguably the third-oldest university in England, having been founded by King George IV and the Duke of Wellington in 1829)
(ii) I fail to find any announcement (or report afterwards) about this talk, and likely there was none in the Web.
(iii) This is the only report (English or Chinese) I can find about this talk of his, despite Mr Teng Biao's twitter: "滕彪 @tengbiao · [15 hours ago; it's 10 am EST, Mar 19] Western gov'ts have political/moral responsibility to support Chinese rights activists &give more pessure [sic] to CCP. I said on BBC Impact."