So, the brown parts appeared after the winter, or after the watering? Was it wilted when you watered it?

Hi, no the brown parts appeared after the winter, just recently I think. I hadn't watered it since last year but after seeing the brown parts decided to water it this morning just in case it was dehydrated or something.

I have found that French lavenders do tend to produce dead stems after winter. Just cut these stems out and then cut the remaining back by about half to two thirds. I have to admit that I'm not a fan as they always look so good when you first buy them whilst in flower but seldom live up to expectations. Lavendula Angustifolia Hidcote or Munstead would be my favourites.

So when the snow (if any) melted, it looked OK, but these brown twigs showed up later? Usually, if it is just slightly drought stressed, the leaves press closer to the branch, to save water. More severe drought, especially when the plant is actively growing, results in the leaves drooping limply downward. After that is usually when you find dead branches, though that can also be caused by collar rot, which is a consequence of watering too often.

Just a general comment - lavender normally grows wild in free draining soil (flourishes in the Mediterranean climate) It shouldn't normally need watering at this time of year.
From the position of the dead stems possible that a dog or cat sprayed it.

Thanks to everyone for the advice. I only noticed the brown parts a few days ago, they may have been there for time, I'm not really sure as to be honest as I didn't really take much notice over the winter period. All six plants have some brown parts to them so probably not caused by animal urine. I thought perhaps the brown parts had been caused by plant dehydration which is why I watered it for the first time in about 4 or 5 months (it's been reasonably wet here over the winter). So is now the time to cut the entire plant back? Or do you wait for Spring proper?