[LT] 1918 m. susikūrus nepriklausomoms Lietuvos ir Latvijos valstybėms, Lietuva neturėjo priėjimo prie jūros. Palanga ir apylinkės, 1819-1921 m. priklausiusios Kuršo gubernijai, atiteko Latvijai. Remiantis etnografiniu principu buvo siekiama pakoreguoti Lietuvos sienas Kuršo gubernijoje. Tarpvalstybiniam sienų ginčui spręsti abi šalys 1920 m. rugsėjo 28 d. pasirašė arbitražo sutartį sienai nustatyti. Superarbitru abiejų šalių sutikimu buvo patvirtintas Simpsonas. Komisija dirbo nuo 1920 m. gruodžio 29 d. ir 1921 m. kovo 20 d. Simpsono sprendimas atiduoti Palangą Lietuvai buvo galutinis ir neskundžiamas. 1921 m. buvo sudaryta tarpvalstybinė Lietuvos-Latvijos sienos sutartis.
Tarpukaryje jam įteiktas Lietuvos Gedimino ordinas. Palangoje Simpsono garbei pavadinta gatvė. Čia 2021 metais atidengtas ir atminimo paminklas.
[EN] In 1918, after the establishment of independent states of Lithuania and Latvia, Lithuania did not have access to the sea. Palanga and its surroundings, which belonged to the Courland Governorate from 1819 to 1921, fell to Latvia. Based on ethnographic principles, there was an effort to adjust Lithuania's borders in the Courland Governorate. To resolve the interstate border dispute, both countries signed an arbitration agreement on September 28, 1920, to establish the border. Simpson was appointed as the super-arbitrator with the consent of both countries. The commission worked from December 29, 1920, to March 20, 1921, and Simpson's decision to transfer Palanga to Lithuania was final and not subject to appeal. In 1921, an interstate treaty on the Lithuania-Latvia border was concluded.
During the interwar period, he was awarded the Order of Gediminas in Lithuania. A street in Palanga was named in his honor. In 2021, a monument in his memory was unveiled there.
