The 'no pets' clause is the default setting in most rental contracts so unless the landlord has actually specified s/he won't allow pets, there's always hope. Bribery (in the form of a larger deposit and/or agreeing to pay for the carpets to be professionally cleaned at the end of the tenancy) is always worth trying.
Some landlords are willing to accept cats but not dogs, so it's worth asking them to be specifiic about the sort of pets they won't allow.
If you're going through a letting agent, it's worth mentioning to them that you have pets as they will try and find a suitable property for you. Letting agents are generally far better than estate agents, because they usually manage the property for the landlord and will be your contact with him/her, so it's in their interest to get the right tenants. (Our agent was great, and I even got them to change our contract to specify two cats instead of one!)
Sorry to pick but this isn't strictly true, statistically in this country, very few landlords choose to have their property managed, regardless of it being an estate or letting agent, estate agents do also offer a management service, it's just British landlords use agents in general for a tenant find service only and prefer to manage themselves.
I always keep the cats issue to myself when I've rented through an agency. I get the agent to like me, then they are a lot more likely to work on the landlord when they realise they have a good tenant.
Offering a larger deposit is usually the way round it. offering professional carpet cleaning is good too lathough the standard "pets allowed" clause generally states something to that effect anyway.
It can be really difficult, I remember our negotiators working very hard for pets to be allowed, trying every trick in the book and the landlord just would not give way at all. In fact, I've been through it myself when I was a property manager!
I'm not going to lie, it can be very very difficult, I've just got really lucky I think with rentals as I've never had a problem. Keep trying the free ads too, you just have to explore every avenue available to you. Oh and make sure to be completely happy to have them contact your previous landlord you had pets with and mention it on viewings.
This issue crops up on MSE (MoneySavingExpert) forums regularly; it seems quite a few pet owners have been able to come to an arrangement with a landlord by offering a larger deposit plus good references. Letting through the same agency or same landlord is also worth exploring, as they should know that you are reliable and respectful tenants.
Do bear in mind that many long leases (contract between owner of a flat and owner of the block) specify no pets OR no pets without written permission (usually £££). Some landlords are unaware or ignore such clauses but they CAN be enforced. Having said that, I have only ever heard of that happening with pet that are allowed into shared areas such as corridors or gardens or are 'noisy' (some older flats have very poor sound insulation).
As a general point I find it is most productive to bypass letting agents where they unhelpful - they won't always pass messages on when there is nothing in it or them bar extra work. IMO the best way of doing this is by e-mail - addressed to the landlord but sent to the agent. If you ask open question (not a yes or no answer) then you have the best chance of a genuine answer. Otherwise you could consider asking each agency which properties they have that are the size you require and allow cats, rather than asking to view one you like the look of.
There is a standard "no pets" clause but if pets are agreed you just ensure they take this out and replace it with the pets allowed clause which details exactly what and how many of them is allowed.
It's very easy to say bypass the agent but unless it's the landlord showing the property (very rare) then the agent will not pass on landlords details or forward on emails sent via them. The landlord is after all paying them a fee for letting their property and the agent isn't about to take themselves out of that fee earning loop!
