BHARUCHA, J. :- This writ petition, which has been referred for bearing and final disposal to a Division Bench, concerns the compulsory purchase by the Maharashtra State Electricity Board, respondent 1, of the undertaking of the Thana Electric Supply Company Ltd., petitioner 1. Principally, the petition challenges the constitutionality of the Electricity, (Maharashtra Amendment) Act, 44 of 1976.

2. To appreciate the rival contentions a chronology of events needs to be set out.

3. On 14th September 1927 the Government of Bombay by notification issued a licence under the provisions of the Electricity Act 1910, known as the Thana Electric Licence, 1927, to Messrs Phiroze Erachshaw, Behramji Muncherji and Rustomji Pestonji carrying on business in partnership in the name of M/s. P. Patel and Company. Clause 11 of the said licence (which was later renumbered clause 12) read thus:

"Purchase of undertaking 11. (1) The option of purchase given by S.7 of the Act shall first be exercisable on the expiration of 50 years from the commencement of this license and thereafter on the expiration of every subsequent period of twenty years during the subsistence of this license. The value of