The Britannia Inn, Elterwater, is a great place for dogs and people. Its located in the middle of the village, right alongside the Cumbria Way, and at the intersection of several paths. Its a good base for walking in the Langdale Valley. There's a nice dog dip in the river just over the village green in case your Lab comes back muddy! We spent a week in Elterwater and ate there every night. It was a good place to meet other dog owners and compare notes on local walks. Its the only pub I've seen that sells dog chews over the bar! For people: The bar food is very good with a varied menu that changes nightly. In addition to the normal beers they have another seven taps for local brews, and change them regularly. http://thebritanniainn.com/
I thought I'd update this. The Brit has just been awarded 'Best Pub in the Lake District' by the readers of Trail magazine. Having sampled many pubs up there I was please to see that the three I voted for ended up as the top three!
Totally agree..have been there with my huge Newfie in the past...it was perfect and he was most welcome
The White Lion in Patterdale is another great dog friendly pub. Great food for us humans. Each time we visited a saucer of dog biscuits was bought to our table for Mabel with a huge jar on the bar if a top up was needed. There are also dog towels in the porch. Some great walks in the area too.