The timings I have are:
1S26 - 02:00 (Northbound Glasgow/Edb)
1S25 - 22:56 (Northbound Inv/Ftw/Abd)
1M16 - 06:12 (Southbound ex. Inv/Ftw/Abd) **This is prone to very early running**
1M11 - 04:42 (Southbound ex. Glc/Edb)
However, can quite often run early or via an alternative route in which case it may not pass at all.
Next signal check past Watford Junction isn't until Crewe.
At LTV, it will literally be a glimpse because it will be passing through at around 80mph...