I have a contract that states that I started working for the company in May 1994.
If that is what your current contract states then you should be fine. If it an old contract then it is irrelevant. I have old contracts of employment from previous employers, it doesn't mean I still work for them.

That's what I was fearing, but I still work in the same building with the same brand name, doing the same job so I still worked for that company brand name but it's owned by a new company. On the website is has the brand name everywhere, but in small print on he page where it says shworooms are it says the 'brand name' is a division of the 'new company name'. Going by how the CEO of the new company is, I'm pretty sure that they will try and get away with paying us the minimum and all my 18 1/2 years will mean nothing. So they can really wipe of 15 years service and you get nothing for that from anyone?
When buying a company from the administrators you could well agree to retain the property and the assets. Again this is irrelevant to your case. The property would almost certainly be run on leasehold so you just agree to continue with the landlord. It would still be the same brand of vehicles, even the brand name would have value if well established and respected - which you say it was.

Buying a company in administration is similar to buying something in the sales. Significantly reduced price and you can pick and choose who you would want to offer employment to. Previous length of service is wiped out.

I myself e-mail insolvency practitioners every now and again hoping to pick up new business on the cheap.

That's what my meeting up in London tomorrow is about. It wasn't my ideal job and I was looking to move, so if I did get the 18 years statutory redundancy, then at least I'd get a pay-out (and could pay off some bills) and have a while to find a new job, but if not, then basically I'd get next to nothing and would be more interested in staying with the company as I wouldn't have long to find a new job and have to start paying bills with no way to pay them without a job.
Length of service aside, if your employer offers you a 'reasonable' alternative position which you then turn down you will not get any payout.

Going back to when your previous employer went into administration, you would have been entitled to a redundancy payout then.

private companies will do everything they can to riggle out of a contract
In my experience most employers that I have worked for have been very fair. Similarly the employers/business owners that I know adhere to the law.There are good and bad employers as there are good and bad employees.

Good luck with your meeting SEB.

Andy and Grace