Hello,
a very intact car it seems. Probably very original as well and carefully restored/conservation work done. How many "original" Thetas around? As far as I remember it was sold at auction some time ago, at least I saw it at Bonhams' Grand Palais auction not long ago (try the lot finder).
It will be most interesting to see how many people will bid for it. Seeing very very few people at auction bidding for prewar cars in general, remember the beautiful 8-cylinder Delage convertible, fully restored that sold recently for slightly more than 100.000 Euros? Hardly possible to restore the car at this price. Or the wonderful Voisin C1 project at the Artcurial auction in February that did not attract a single bid?
I expect this Theta to sell for considerably less than the estimate (maybe post-auction).
J