Hi Alan,
The short answer is, not exactly. When your mum died, under the will, your brother (the executor) becomes the personal representative of your mother. This means, title effectively transfers to your brother. This is necessary in order for the executor to deal with assets, collect debts, pay creditors, set any property up for sale, appoint an agent etc.
However, your brother does this on behalf of all beneficiaries under the will. This means, he owes a fiduciary duty toward the three beneficiaries and if he misappropriates your mother's assets, or does something against the interests of the beneficiaries as a whole or makes a profit without the beneficiaries' consent (other than a small remuneration and reimbursement of costs for being executor of the will) then he will have breached his fiduciary duties. When this happens, you (and other beneficiaries) can sue him to reclaim your loss and the misappropriated assets. A fiduciary duty is a strong duty.
Since your brother has title to the property, he can sell it without the consent of the beneficiaries (think of a trust, where the trustee does not need the beneficiaries' consent for every investment decision they make under the trust). Further, before the executor distributes to the beneficiaries, the beneficiaries actually have no interest in the property except for a right to ensure that the executor deals with the property properly (i.e. in your interests).
Having said that, it is good practice to let the beneficiaries know what is happening, maintain good communication and seek their consent (or involve them in the decision-making process) if possible. Also, your brother should obtain probate. Probate is the court declaring the will as the final and valid will of your mother. Without probate, if your brother deals under the will and later, it turns out there is another will or that your brother did not follow the will's instructions, he will be personally liable for any loss due to this.