Previously a British Conservative Party politician who was the Member of Parliament (MP) for Ynys Môn from the 2019 general election until 2024.

[4] As a teenager, she worked as a dolphin trainer at the Woburn Safari Park for Terry Nutkins's BBC children's television series Animal Magic.

[13] Crosbie was chosen after the former Brecon and Radnorshire MP Chris Davies, the previously selected candidate, withdrew the day before due to opposition by the local association, and other Welsh Conservatives.

[21][22] In July 2020, Crosbie apologised for errors on her Welsh language website, stating that the machine translation was "not 100% perfect".

[24] In 2020 she successfully campaigned to give Ynys Môn protected status in the UK Boundary Changes review.

An amendment put forward by Maria Miller MP brought Anglesey in line with other UK islands including the Isle of Wight and Orkney ensuring that it would not become a joint constituency with part of mainland Wales.

[27] She campaigned locally for improved broadband connectivity,[28] better availability of defibrillators,[29] a third Menai crossing,[30] reversing the Welsh Government's 20mph default speed limit,[31] a new medical centre in Holyhead,[32] better understanding of the impact of large scale solar farms on rural communities and agricultural land[33] and a new Aldi supermarket in Amlwch[34][35][36] In 2020, Crosbie started the Anglesey Freeport Bidding Consortium[37] following the UK Government's announcement that at least one freeport would be established in Wales.

The Consortium included Anglesey Council, Stena Line (owners of Holyhead Port), Bangor University and M-SParc.

Since beginning her career as an MP, Crosbie has made the case for building new nuclear power stations in the UK.

[52] In the March 2024 budget the then Chancellor of the Exchequer Jeremy Hunt said of Crosbie "Ynys Môn has a vital role in delivering our nuclear ambitions and no one should take more credit for today’s announcement  than my tireless, tenacious, turbo-charged hon friend for Ynys Môn" when he announced that the UK Government through Great British Nuclear would be purchasing the Wylfa site from Hitachi.

[54] Crosbie took several nuclear companies[55] [56][57]including Bechtel, Westinghouse, Rolls Royce and Kepco around Ynys Môn to look at Wylfa.

She launched a survey [62]of local people and contributed to a Westminster Hall debate on large scale solar farms.

[67] Crosbie resigned as PPS in July 2022 in protest against the leadership of Prime Minister Boris Johnson over his handling of the Chris Pincher scandal.

[71][72] Crosbie apologised in June 2023 for attending an event briefly in Parliament while COVID-19 lockdown restrictions were in place on 8 December 2020 which she attributed to a "momentary error of judgment".

[73] Subsequent investigations by the Metropolitan Police and the Independent Parliamentary Standards Authority both found that Crosbie's attendance at the event did not contravene Covid regulations.

[81] In 2020 Crosbie took part in the Parliamentary Armed Forces Scheme and she supported developments [82][83]in RAF Valley on her island constituency.

Crosbie has also led Parliamentary debates on communities served by the West Coast Mainline franchise,[84] the closure of the Menai Suspension Bridge[85] and Freeports in Wales.

[88] Following the Welsh Government's announcement in 2023 that it was axing plans for a third bridge across the Menai Strait,[89] Crosbie started a campaign for a third Menai Crossing[90] citing Welsh Government evidence that not going ahead with the crossing would give "detrimental effects on the economy of the Isle of Anglesey and north west Wales".

[92] In May 2023 she gave away a mile of Union Flag bunting to communities across Ynys Môn to celebrate the Coronation of King Charles III[93] She stated that one of her aims was to bring jobs and investment to Ynys Môn, and welcomed a £175m investment at RAF Valley[94] and a new HMRC Inland Border Facility in Holyhead.