Beware that TTN Mapper only shows gateways that appeared when explicitly doing mapping. (Right, @jpmeijers?) Also, the coverage that is shown is only that of explicit mapping. So, if there’s no regular mapping in some area, then TTN Mapper may not know about all gateways. (So: go mapping! 
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The global map or community maps may show other gateways. But even those maps may be incomplete if gateway owners does not allow the location to be publicly visible.
The Leicester’s community page also only shows an offline gateway, but you might want to join that community and contact its two members, @Jbee (the gateway owner) and @seancuttlefish (not recently active on the forum). See also How to contact a gateway owner?
Aside: note that the right name is “gateway” (not router or network node).