Perhaps the architect used the website's in-built application for drawing the red lines. FWIW, I usually download the digital versions, which are a little more expensive (£21.00 + VAT, I think), and I present this cost as just that on my Invoices - so no mark up. Obviously, time is spent collating and preparing this data, and that charge is instead incorporated into the hours shown on my fee proposal. It's a statutory requirement, but otherwise, for domestic projects, the whole exercise is futile as many of the LPA's with which I work just upload their own maps anyway when the application is validated. That said, I don't think charging £37.00 for this service is particularly excessive (but maybe a little excessive).