I hesitate to add this post, as it may only add to the confusion. And this case has plenty of options, many of which could be swept away if we had a bit more guidance from LE.
DCI Kentish mentioned initially the sightings of someone like Leah was at the Teardrop lakes, and they searched them. The first part is a flow directly from Furzton Lake and I saw them searching this section. Large object cannot flow into the smaller lakes due to grills, but of course a person could fall or be pushed into them. So they were all searched including Culverts under the road.
But given the wide range of times when witnesses said they saw a person who looked like Leah on a phone, it made me wonder if Leah received a call on her way to work around the Lake and wished to delay her normal route, so she continued using the Red Route by the side of the hotel, which goes under Watling street and ends up at the Tear drop lakes. This area has one small public car park but there are lots of large offices with people using the paths to go to those offices. But if Leah then decided to delay going to work and walked back to Furzton Lake it would explain the huge time differences with the sightings. Clearly the time she switched off her phone does not fit in with this unless she only turned off the location part at that time, or as seems unlikely she had another phone. Also given how conscientious her mother said she was, she would probably have phoned in and said she would be delayed arriving at work, and there is no report of such a call. Only added this in as the initial reports mentioned Teardrop lakes not Furzton Lake. I have not stumbled across any retraction or correction of this early reporting.
As a newby to this forum, I am so impressed with the huge and respectful time and energy Ws members put into trying to help.