All Skegness services will be formed of 1 x 153, they're also only operating Grantham to Skegness as the line to Nottingham is closed, that gives you an additional 6 carriages to play with. Services to and from Norwich are operating independently to the rest of the route as they have to run via Melton Mowbray, so that also releases 1 x 158 which would otherwise be shunted off/onto Liverpool services. One Ivanhoe diagram will be covered by a 222/5, so that also releases 1 x 156. I expect some Crewe and Matlock services will also be cut down to 1 car to provide a few extra carriages, plus anything not required for maintenance will be put out into traffic as well.
In short, its taking from Peter to pay Paul, because there is no other way of providing the capacity that will be required.
*Edit* There are quite a lot more seats provided to/from Lincoln this year compared to last, I think its something like a 20% increase on last year.
