It seems like Virgin have a deal on some of their SIMs when taken with a Broadband bundle. Seems a decent offer if you are in the market for a SIM at the same time as a cable bundle...
To get this, select your Broadband bundle, click "Personalise your Bundle" and scroll down to the SIM sections
2500 mins / Unl Texts / 2GB @ £5 per month
2500 mins / Unl Texts / 4GB @ £8 per month
5000 mins / Unl Texts / 20GB @ £18.00 per month
All 4G SIMs on a 12 month contract, and come with the data rollover / free whatsapp deals that come with Virgin.