Elizabeth line with cross-London ticket

[crosscity]

I have bought a Watford Jct-Exeter Central via Paddington Advance ticket. I have collected it and it has the + mark to say I can use it to get from Euston to Paddington.
I'd like to try the Elizabeth Line as I've not yet used it. What is the longest ride on the EL I can make with this ticket. For instance could I catch a Northern Line (City Branch) train from Euston and change at Liverpool St?

 

[Hadders]

Officially you're allowed to take any appropriate route between Euston and Paddington. Euston to Tottenham Court Road and then Elizabeth Line to Paddington is undisputably appropriate. Going via Liverpool Street less so, although it's highly unlikely to be an issue.

 

[gazthomas]

Farringdon might be more appropriate

 

[Somewhere]

Liverpool Street maybe? You'd be unlucky to find a member of TfL staff who have knowledge of the National Rail network to understand the geography. As long as its got the + symbol, you'd be fine.
You could always say you'd got on the Circle Line in the wrong direction accidentally!

 

[redreni]

Liverpool Street maybe? You'd be unlucky to find a member of TfL staff who have knowledge of the National Rail network to understand the geography. As long as its got the + symbol, you'd be fine.
You could always say you'd got on the Circle Line in the wrong direction accidentally!

If you get off the Northern Line at Moorgate and follow the signs for the Elizabeth Line it takes you to the 'Liverpool Street' EL platforms without the need to pass any gatelines or interact with staff, so that won't be an issue.

In the highly unlikely event of encountering anybody suggesting you're not taking an appropriate route, simply pretend to be lost and follow their directions on how to get to Paddington, would be my suggestion.