The EP contains four instrumentals and is a work of musique concrète, sound collage and experimental music, based on field recordings that Weller captured during his travels and everyday life.

Paul Weller had long been a fan of electronic label Ghost Box, and their influence on his music was apparent in eccentric recordings such as "Night Lights" from 22 Dreams (2008) and the lengthy sound collage "Jimmy/Blackout" from the Jawbone soundtrack (2017).

"[1] Weller commented that once he knew Ghost Box were interested in a release, he began storing up ideas, later resulting in a wealth of sounds on the EP that were recorded from his iPhone.

[4] Kitty Empire wrote that while Weller had "dabbled in all sorts of outre soundmaking" since 22 Dreams (2008), with albums "as varied as they were regular", the musique concrète EP is arguably the "strangest of all".

[11] Osborne says that while the EP fits firmly into the musique concrète tradition, it features "subtle melodic undertones", and felt that the project's existence would not surprise those who had kept up with ten years of Weller's "sonic shape-shifting".

[1] In Another Room was partly influenced by Broadcast, whom Weller had long championed in interviews,[10] and has drawn comparison to Delia Derbyshire,[10] and Julian House's work with the Focus Group.

[1] "Submerge" features deft effects,[10] while "Embarkation" originated during the Jawbone soundtrack sessions; Weller said it "didn't work out so I managed to be able to re-do [the track].

[13] In their review, Mojo wrote that while the idea of Weller "releasing an EP of eerie musique concrete" may have seemed highly unlikely a decade or so earlier, 2010s albums such as Sonik Kicks (2012) and Saturns Pattern (2015) had "acclimatised fans to the Modfather's increasingly experimental mindset," which reaches "an apogee" on In Another Room.

[3] Alexis Petridis of The Guardian similarly noted: "It's worth considering for a moment how unlikely the idea of Paul Weller releasing an EP of musique concrète experimentation on a leftfield electronic label would once have seemed.

They deemed the EP "far from perfect", writing of "a sense of Weller shifting palettes – embracing a slightly uncomfortable mirror of a 1973 dreamscape he once rebelled against – but still working within rules".

[3][4] Pat Carty of Hot Press wrote that while the EP may have baffled Weller's fans, it acted as a "signpost" of his change of direction, noting that the musique concrète breakdown in "Mirror Ball" continues the musician's experimentation.