A Beddoe application is a type of application to the court, made by trustees, for directions.
The trustees ask for permission from the court to litigate (or continue to litigate) against someone not a party to the proceedings.
There is a main application, which is the substantive case itself, and the Beddoe application.
Common Beddoe applicants are usually trustees, but also include executors, and those who administer the estate of a deceased person. What is required for a Beddoe application is a fiduciary duty.
The advantage of making a Beddoe application is the potential costs protection. If a Beddoe application is made, and the court is satisfied that the applicant trustee/ executor etc. is justified in making the application so that a claim may be made/ defended, then the court will indemnify that applicant.
This means that the court will order that the trustee can take from the trust fund not only his own costs, but any costs against him in the main case.
To quote In re Beddoe, Downes v Cottam  1 Ch 547 (CA), Lindley LJ stated
“I entirely agree that a trustee is entitled as of right to full indemnity out of his trust estate against all his costs, charges, and expenses properly incurred : such an indemnity is the price paid by cestuis que trustent for the gratuitous and onerous services of trustees; and in all cases of doubt costs incurred by a trustee ought to be borne by the trust estate and not by him personally”
So, if a trustee makes an application to the court in advance and is granted an indemnity, there is no risk of costs.
If there is no application, the risk of adverse costs orders remains. The position seems to have been the same since the Beddoe case, where Lindley LJ added
“But, considering the ease and comparatively small expense with which trustees can obtain the opinion of a Judge of the Chancery Division on the question whether an action should be brought or defended at the expense of the trust estate, I am of opinion that if a trustee brings or defends an action unsuccessfully, and without leave, it is for him to show that the costs so incurred were properly incurred. The fact that the trustee acted on counsel’s opinion is in all cases a circumstance which ought to weigh with the Court in favour of the trustee; but counsel’s opinion is no indemnity to him, even on a question of costs.”
For help with Beddoe applications, contact the probate team via firstname.lastname@example.org