Good Friday

Out early to get into Waitrose just after they opened so that I could get to the fish counter before the hordes, as I wasn't sure what to get and wanted a good choice. With their normal Friday '20% off fish' deal coupled with a 10% discount card they recently sent me I got a really good deal. Back home we managed a slightly longer walk up to this point; all good progress. Unfortunately it started raining before we got back home and has been raining solidly ever since. How can you tell it's a Bank Holiday?