Because they were going to host the second leg originally and, IMO, it should be that way (both teams might agree to a switch, which would be fine, but they both agreed to the original dates).
Leicester website says (in the report of Batchelor signing as Nick Morris's replacement:
"Morris failed to comply with the Alcohol and Doping testing procedure when randomly selected prior to Wednesday’s fixture between Birmingham and Glasgow, and he will be summoned to attend an SCB Disciplinary Court hearing." This implies (to me, at least) he refused to take the test.
I can't be bothered to trawl through the rulebook (!!), but I'm pretty sure that if a rider who was originally riding in the League above, but becomes available, you can switch back to your rider riding, rather than use a guest.
Comment from Birmingham CEO Nigel Tolley "We understand the frustration and disappointment of the supporters – we share that right now and we will update everyone on the situation with Nick as and when we can.”
Both on BSPL report and Birmingham Speedway website report.
Not in the top 10:
The top ten wettest counties in England are (in descending order): Cumbria, Lancashire, Yorkshire, Northumberland, Durham, Lincolnshire, Derbyshire, Nottinghamshire, East Sussex, and Kent.
Source: https://www.historic-cornwall.org.uk/is-cornwall-the-wettest-county-in-england/