There are "robust" indications that a single British energy market will continue in the event of Scottish independence, according to a renewable energy investor.

A continuing joint Great Britain electricity market is seen as a "natural outcome" if Scotland votes Yes, The Renewables Infrastructure Group (Trig) said in its interim results.

Trig, which recently added former E.ON and Royal Dutch Shell executive Klaus Hammer to its board, has about a quarter of its portfolio in Scotland.

It told investors: "The UK Government has not formalised contingency positions for a Yes vote in the independence referendum.

"Thus, there is an absence of clarity on what aspects of the electricity and renewables regulations and policy would change, and what any new arrangements would be following any secession.

"While there can be no certainty that the politics evident in some pre-referendum positioning could not spill over into enacted policies potentially damaging to the renewables markets, and therefore to Trig, several factors contribute to a robust view on the future of the subsidy regime in a separate Scotland, should this be the case:

"The capability for Scotland to deliver a substantial part of the UK's overall renewables and power requirements - mainly from onshore wind which generally operates with high capacity factors and therefore economic efficiency in Scotland. In contrast, in England the deployment of renewables is running into increasing levels of planning challenges.

"The economic significance of the renewables and broader energy industries in Scotland, coupled with the cost effectiveness of onshore wind in Scotland versus other renewables options of solar PV in England and offshore wind.

"The importance to both the UK and an independent Scotland to honour their commitments. The UK has an excellent and long-standing reputation in the credit markets. The continuing UK and Scotland will have a strong desire and motivation to maintain this standing at this important juncture.

"The likelihood, as generally proposed by industry commentators as a natural outcome, of there being a continuing joint GB electricity market following any independence given the historical position and physical adjacency."