Not a party - Appeal

"It is well settled that a person who is not a party to the suit may prefer an appeal with the leave of the appellate Court and such leave should be granted if he would be prejudicially affected by the judgment."

Jatan Kanwar Golcha v. M/s. Golcha Properties Private Ltd., AIR 1971 SC 374

Presently, it is apt to note that Sections 96 and 100 of the Code make provisions for preferring an appeal from any original appeal or from a decree in an appeal respectively. The aforesaid provisions do not enumerate the categories of persons who can file an appeal. If a judgment and decree prejudicially affects a person, needless to emphasize, he can prefer an appeal.

Hardevender Singh v. Paramjit Singh, 2013 AIR SC 856

A person who is not a party to a decree or order may with the leave of the Court, prefer an appeal from such decree or order if he is either bound by the order or is aggrieved by it or is prejudicially affected by it. As a rule, leave to appeal will not be refused to a person who might have been made ex nominee a party.

see Province of Bombay v. W.I. Automobile Association, AIR 1949 Bombay 141;

Heera Singh v. Veerka, AIR 1958 Rajasthan 181

Shivaraya v. Siddamma, AIR 1963 Mysore 127

Executive Officer v. Raghavan Pillai, AIR 1961 Kerala 114

In re B, an Infant (1958) QB 12

Govinda Menon v. Madhavan Nair, AIR 1964 Kerala 235