Teesside? Humberside? Outside of England, Prestwick.
Teeside would require running any traffic to the port through built up areas as well as major construction. I have been involved in the potash tunnel up there and it was a nightmare getting it through planning & the campaigners Humberside is a better option but it isn't exactly surrounded by potential employees and so would still be less attractive than Manston with is close proximity to London and the channel.
As for Prestwick, that's too far away to be viable under the same plan.
Again, it was merely me musing about what a waste of ready made infrastructure it is in a prime position for Euro access. I have no specific idea of it's use and maybe there isn't one. It just seems such a shame to let it go when we struggle so much to build anything similar.
In a post Brexit world I can't help but think it is an asset we should try to preserve.