when you pass your driving test you are automaticly entitled to tow a caravan, trailer etc as long as it does not exceed a certain kerb weight and is correctly constructed.
ragardless of what insurance you have you will be covered to tow. the only time you will not be covered is if you have arranged with your insurers not to tow in order to reduce your premium.
therubster,dont talk a load of crab.a taxi policy is a special policy and towing would not be a automatic inclusion on it.
also towing a caravan is not a automatic entitlement on your licence,when you pass your test now.
as i said check with your insurer to be safe