Woodworm - Have I bought a worm sanctuary?

[muttley9050]

It just adds character to the old boards. Where they expensive?

[Boo Who?]

My guess is the floor was cleaned regularly and it is just a build up of scunge that has gone through the faults in the varnish. If it was wet washed the dirt would automatically flow and fall into all the low points however small they are and with time that dirt has started to stain the wood slightly. I think if you sanded a little harder you could remove most of the marks entirely.
Just a guess though...