The boundaries of Greasby township are:-
west - Greasby Brook
north - Greasby Brook, Arrowe Brook
east - Arrowe Brook, the stream on the west side of Arrowe Brook Lane**, Arrowe Brook Lane
south - Arrowe Brook Lane to Irby Mill pub, Hillbark Road to Greasby Brook
**It is probable that this stream was the original Arrowe Brook prior to the upstream diversion of most of its water in the 1830s to provide the ornamental stream and lake in Arrowe Park.
There are local Sites of Biological Importance (SBI) - Greasby Copse and Ponds at grid reference SJ258866, Upton Bridge Wood aka Millennium Wood SJ265875, Arrowe Brook Farm Ponds at SJ265865 and the former RAF Camp at SJ243877.
Wirral was historically part of Cheshire (long before the Domesday Book in 1086). In 1974 the government changed the boundaries of many counties for administrative purposes. This change was unpopular in Wirral, which was parted from Cheshire and incorporated into the newly formed Merseyside region.
Wirral is still in Vice-County 58 (Cheshire). Vice-Counties (permanently defined geographical areas) were established in 1852 in order to give continuity to historical statistics (e.g. wildlife counts) so that they would be unaffected by politicians who can change political boundaries at whim.