This paper presents the history of the atmospheric electricity measurements at Lerwick Geophysical Observatory. In particular, there is a detailed description of efforts to record the atmospheric potential gradient at the Observatory and maintain high quality of the measurements. From this point of view, the paper is comprehensive, and contains many interesting details. Perhaps examples of recordings could be also shown in other figures.

Less has been said on contemporary atmospheric measurements throughout Europe and worldwide, albeit this is not the main subject of the article. Some background, in addition to the situation with the atmospheric electricity measurements in the UK, could have been added in the introduction.

There is only a couple of technical errors, which can be easily dealt with on the final preparation of the manuscript for publication, e.g. line 123: “Figure 4” could be put in brackets, line 200: a space missing after “tests”. In addition, in line 237, at least one of the range values of the resistor’s resistance should be corrected.

Review of: "Atmospheric electricity at Lerwick Geophysical Observatory" by Harrison and Riddick [Paper # hgss-2022-6]

This is a well-organized, clear and lucid work, that describes the history of electrical measurements conducted at the Lerwick observatory in the Shetland Islands. The text is supported by images and drawings and gives a splendid description of the achievements of that remote station.

I still find some issues that require elucidation, and I would suggest a minor revision is made to the present text. Some clarifications are also needed as detailed below. After these are responded to, the manuscript can be accepted for publication.

Major Comments

1. The title of the manuscript does not include the word "observations" (or "measurements"). Clearly there is "atmospheric electricity" in Lerwick and anywhere else, but what makes this place unique is the fact that actual scientific observations were made there for a prolonged period. I suggest that the authors consider adjusting the title of the manuscript accordingly.
2. At least some quantitate data and perhaps an original record from Lerwick should be presented. What was the average (fair weather "background") PG value measured there and was there indeed a clear diurnal Carnegie-like cycle? This should come after section 4.3.
3. I salute the author's bold parallel between the detection, at Lerwick, of nuclear tests' effects on atmospheric electricity and the discovery of the ozone hole in the 1980s by the British Antarctic Survey at Halley Bay in Antarctica (lines 339-340). I whole-heartedly accept this analogy and support the authors' quest for renewing electrical observations there. However, this part requires elaboration:

• • Concerning the effects of radioactive contamination on the PG measurements, the readers would benefit from graphs showing the onset of the electrical changes observed at Lerwick, perhaps marking specific dates of nuclear explosions. See for example Huzita (1966) that showed data obtained after the large soviet nuclear tests at Novaya Zemlaya on October 30, 1961. Pierce (JGR 1972) reported changes in PG from 6 stations, including the UK, for the period 1950-1964.
  • Lines 217-223 - It is confusing that the unnamed "summer student" reported a 6% increase to the PG, while the opposite should be expected if the conductivity is increased due to a radioactive source being introduced to the area (as per Ohm's law). Reference should be made to the work of Lee Harris (JGR, 1955) and Holzer (JGR, 1972).
  • The statement in line 219 "This was probably linked to the surface radioactive deposition" in 1964 and "some confirmation was found…the freezing (of the lake) in February 1966" and the short mention of the direction of the prevailing winds there seem a little speculative. As this paragraph holds key importance to the topic above, a better and more in-depth explanation is needed.

Minor comments

1. In section 2.2 I recommend adding a map showing the location of Shetland and specifically the location of the Lerwick observatory, to give readers a better geographical context. This is highly needed as the text refers, for example, to Loch Trebister, Point of Trebister and to the Sands of Sound, when describing the different components of the observatory (lines 68, 179, 180). Also the location of the Windscale test site (line 336) should be marked.
2. The description of the various houses (buildings) in lines 64-70 and their numbers is not matched against either Figure 1 or 2, which do not overlap and make orientation quite difficult. A better description is needed to coordinate between the text and the image and drawing.
3. Line 255 – was the Soviet Union (USSR) indeed responsible for publishing the UK atmospheric electricity data? One wonders how this came about. Please elucidate this intriguing fact.
4. Section 4.2, lines 285-287 – it is interesting to learn if there were instances in the data when the PG exceeded the threshold of 1 kV/m? One wonders what would cause such strong deviations from average values and whether they are related to fog, volcanic ash or pollution.