Tanfield Group reported strong progress in its two investments, Snorkel International Holdings (SIH) and Smith Electric Vehicles Corp (SEV), but warned that a longer-term "risk of failure" remained.Tanfield attributed the success in the year to December 2014 to its business strategy of combined manufacturing and licensing of its technology.While Tanfield does not hold board seats at SIH or SEV, it holds stakes of 49% and 5.76% respectively.SIH saw a reduction in supplier constraints, bolstering production and its spares business to a more favourable market backdrop for its products.Meanwhile, SEV benefited from an exclusive joint venture established in May with Hong Kong stock exchange listed Electric Vehicles Limited, which supports research, development, production and distribution of its all-electric vehicles."During the year both of the investments made progress which the board feels brings the realization of value a step closer. The current combined value per share of investments is 33p per share," said chairman Jon Pither.However, he went on to warn: "The board takes the view that while there has been progress made by both Snorkel and Smith, there is still a risk of failure. The board will continue to fulfill its obligation to its shareholders in seeking to optimise the value on its investments."Tanfield's status was moved from a manufacturing entity to passive investment company last year, following disposals in 2009 and 2013.As of 11:30 BST, Tanfield was trading 0.4% lower at 22.5p.