Pay off mortgage or not?

[Mortgage]

i am a regular contributor to PH, but for this question have re-registered to keep some privacy ,as i am going to talk about very specific personal circumstances.

my question is whether i should pay off my mortgage or not.

details as follows.

i am 35, own a house valued at £800k, mortgage of £300k, costing me £1400 per month interest only.

i have 3 houses that i rent out that are fully paid off that gives me a take home of £1000 per month (ie after all expenses, tax, agency fees etc). these have been rented out for around 10 years so this figure is accurate.

if i were to sell these houses, after tax etc etc, i would be left with about £340k.

so the question is, sell and pay off, or not? business head says don't pay off, whereas the heart says pay off.

i would welcome all comments / ideas to help me make up my mind.

[Mortgage]

please expand on your thinking

[Mortgage]

goochie said:

Dont sell. Its your pension

assuming all things stay relative, it's not much of a pension... £1k per month? think i can do better than that... i'm working on building a separate pension pot of around £1.4m

[Mortgage]

point to mention that i didn't make clear, and that is that the rental properties are all in my ltd company name. taking money out is therefore not so straightforward. ie it would have to be as a dividend, for which there are obviously tax implications.

how does this point effect your opinions

(and thanks by the way for all your very useful comments)