The B1225 and B1183 form a north-south link through Lincolnshire and can be incorporated into any journey between Yorkshire (or points north) and East Anglia. These are excellent driving roads and also provide a chance to see the Lincolnshire countryside, which is a lot more interesting than it's sometimes given credit for - it's not all flat for a start!
These roads can also be a surprisingly quick way of completing north-south journeys when the A1 is clogged and are a lot nicer than the broadly parallel A15 and A16 which always seem to be unpleasantly congested whenever I use them. And don't be put off by the fact that these are B roads; they are a lot better than many 'A's and, at least at the times I have used them, they have had little traffic on them. This description of the route runs from north to south.
It's best to join the B1225 at Caistor, which is about ten miles south of the Humber Bridge. This is a relatively fast road with long sweeping curves that takes you over the undulating Lincolnshire Wolds (no, I'm not sure what a wold is either). On my last run along this stretch yesterday, I saw a lot of new road safety signs aimed at motorcyclists; I didn't encounter any, but the B1225 does look like ideal bike country. It doesn't pass through any significant towns, but a short detour will take you to Market Rasen or Louth.
A minor bonus is that the B1225 also passes the base of the Belmont (TV) transmitting station. You've probably never heard of it but this is the tallest structure in Britain, and, according to some accounts, in Europe. Apparently, it's an identical twin of the old Emley mast that famously iced up and collapsed in the late sixties. This photo, taken yesterday, shows it disappearing into the mist; it's a guyed structure, and some of the guy-ropes can just about be made out here (click on the picture to see an enlarged version).
The B1225 eventually joins the A158 near Horncastle, which is certainly worth a look; like the other towns in the region, it's very charming in a slightly frozen in time, fifties sort of way.
Just to the south of Horncastle, the B1183 starts in an appealingly twisty fashion - there's some fun to be had here - but after a few miles, it opens up, leaving the Wolds behind and tracks for miles beneath the 'big sky' for which the Fens are famous on a series of very long, fast straights.
Incidentally, the B1183 offers an unusual opportunity to visit New York and Boston within the space of about half an hour; New York is a small place signposted off the B1183 to the west, while Boston is the road's southern terminus.