What’s the cheapest way to invest in one company's shares, via an ISA?

Hi Peter, All Stock & Shares ISAs enable you to invest in an individual share, including most online providers such as AJ Bell Youinvest, Interactive Investor and Hargreaves Lansdown. The key difference will be the fees you will pay. For example: Interactive Investor carry a quarterly fee of £22.50, plus a trading fee of £10 for buying and selling (this reduces to £6 if you are doing frequent trades).

AJ Bell Youinvest charge 0.25% per annum, plus £9.95 per trade (reduced to £4.95 if there are more than 10 trades in the previous month). Hargreaves Lansdown is 0.45% per annum, capped at £45 per annum, with trading costs of £11.95 per trade (for 1st 9 trades), and reducing to £5.95 for trades of more than 20 per month. Hope this helps.