Butler and Alsop provide a clear and thorough explanation as to why our suggestion (Simms & Ernstson 2019), that the Lairg Gravity Low might be a buried impact crater translocated from further east, is incompatible with what is known of the structure of northern Scotland, and I concede that in this particular scenario they are probably right. My original paper (Simms 2015) was based largely on field observations that, amongst other things, indicated that the Stac Fada Member impact ejecta preserved at outcrop had come from the east (despite claims to the contrary by others; Amor et al. 2008, 2019). When subsequently I became aware of the LGL I realized that its …