Can you confirm that you were not a shareholder in your late father's limited company please and that you received a cash sum of £66,000 from the estate.
You appear to have inherited a quarter of your father's shares as opposed to the company being liquidated into his estate and payments to you and your siblings being made therefrom. If that was the case, the cost of the shares for CGT purposes would be their value when your father passed away. Assuming the payment was made after a formal liquidation, ie where a liquidator was appointed, as opposed to an informal liquidation, it is a capital payment. You effectively disposed of your shares and so you should disclose the £66,000 as the proceeds of the liquidation of your shares in the capital gains section of your tax return. I'd be surprised if there was much of a gain.
I hope this helps but let me know if you have any further questions.
Just a final note.
I would have expected the accountants to have arranged matters in the most tax efficient manner.