(1) PURSUANT to the decision taken by the Ministry of Home Affairs, government of India on 2/05/1961 an Expert Committee was constituted for regulating and controlling the urban development. On the basis of the report of the Expert Committee certain decisions were taken which included one relating to the allotment of land to entrepreneurs desirous of setting up industries. This function was assigned to the Delhi Development Authority. An Advisory Committee was set up to advise the Chief Commissioner in regard to the allotment of plots to industrialists who were required to remove their existing factories from the present locations to the industrial zone. One category of those entitled to allotment at pre-determined rates was a cooperative society. As a general policy the disposal of developed lands was to be by public auction except in the cases where land was required to be allotted at pre-determined rates i.e. rates determined on the basis of cost of acquisition and development plus certain additional charges to be charged on slab basis. On 24/08/1962 the respondents formed into a cooperative society and applied for allotment of land to its members. Out of the 39 members, 6 members had already established industrial units while the remaining 33 proposed to start new industries on allotted plots. The scheme prepared was for allotment of plots on the basis of a perpetual lease. On 1/10/1962 the society was informed by the Housing Commissioner that land would be allotted to it at fixed prices admissible to industrial cooperative societies. This was followed by a decision taken on 18/03/1968 that the 6 members would be allotted land at the reserved rate whereas the remaining 33 will be allotted land at commercial rates. Pursuant to the said decision the society was informed that the prices fixed for the 6 existing unit holders was Rs. 37.00 per square metre and for the remaining 33, Rs. 55.00 per square metre. Individual offers were forwarded to the members of the society. On 23/02/1970 the society conveyed its acceptance of the terms and conditions of allotment by a letter but subsequent thereto some dispute arose between the members of the society and the Delhi Development Authority as regards the rate at which the allotment should be made; the members insisting on a flat rate of Rs. 20.00 per square metre. This request of the society was not accepted by the Delhi Development Authority and the same was conveyed on 14/12/1971 with a directive that the written consent of the. members for acceptance of plots on the terms earlier indicated should reach the Delhi Development Authority within three days. The society was also cautioned that the offers would be withdrawn if the consent letters were not received within the stipulated time. Despite the same a fresh offer was made in June 1972 pursuantant whereto some of the members made the payment. The meeting of the society was called on January 3, 1972 and its decisions were communicated to the Delhi Development Authority but the latter took the stand that since the consent letters were not received within time the offer was treated as closed. Thereupon the society and its members filed a writ petition in the Delhi High court praying that the Delhi Development Authority should be directed to make the allotment at the pre-determined price. In the counter filed by the Delhi Development Authority the iatter contested the claim of the society and its members and contended that plots could not be allotted to all the members at the pre-determined price and that the price of Rs. 37.00 and Rs. 55.00 per square metre respectively fixed for the two categories of members was reasonable and since the society had earlier communicated its acceptance of the said terms it was estopped from resiling therefrom. The learned Single Judge in the High court who heard the petition applying the rule of estoppel held that the Delhi Development Authority was bound to allot plots on a perpetual lease b