In my mind a visit would constitute a period of something up to or less than a month.muditmalhotra wrote:I know cases where a long term visa was issued in similar cases.. hence I think staying 4/5 months is no issue ..... I hope!
That said I do know extended family friends, who have travelled to the UK to visit family for periods longer than that, so what I gather is that it would depend a lot on the individuals circumstances and how they present their application. Strong history of previous frequent travel (& compliance with visa terms and conditions), consistency in what is stated when applying for the visa, what is stated to the IO at point of entry, and then leaving the country on time as initially planned. Proven and on-going strong ties to their home country with evidence to support this all play a key part in my view. Other than that you have the standard requirements which I'm sure you are already aware of having had them apply for several visit visas in the past.
If you are confident about the above, and are not overly worried about forfeiting the difference of visa fee in the event the HO decide to grant a visa validity period less than what was applied for, then you could opt to apply for a long length visa of your choice. My personal choice would be either 2 or 5 years depending on your personal view on the associated risk.